Cardiogenic Shock

Meet the patient

A 64-year-old man is in the coronary care unit, six hours after a primary PCI for an anterior STEMI. The stent is open, the pain has gone, and the team is reassuring his wife — when the nurse notes his urine output has stopped and he has become confused and restless.[1]

His blood pressure is 88/60, his heart rate 118, his peripheries are cool and mottled to the elbows, and a bedside lactate comes back at 5.2 mmol/L. The chest has bibasal crackles. The registrar reads this as "blood pressure holding, probably just a bit low after the procedure" — and that is the moment the spiral deepens, because the cuff is the last thing to fall.[1]

The exam question hiding in this bed is cardiogenic shock complicating acute MI, and the lethal habit it exposes is treating the blood pressure instead of the perfusion. Everything below exists to make you stage the patient with SCAI, defend the MAP with an inotrope and a vasopressor, and reach for early revascularisation and mechanical support before the spiral is irreversible.[6][13]

What cardiogenic shock is — and why the cuff is the last sign to fall

Cardiogenic shock is a clinical syndrome of inadequate tissue perfusion due to cardiac pump dysfunction. The heart cannot deliver sufficient cardiac output to meet the metabolic demands of the body, despite adequate or even raised intravascular volume.[6][13]

The most widely used diagnostic criteria are those of the SHOCK trial registry, refined for acute MI complicated by shock:[1]

• Systolic blood pressure below 90 mmHg for at least 30 minutes, OR requiring inotropes or vasopressors to maintain SBP at least 90 mmHg;
• Cardiac index below 2.2 L/min/m2 of body surface area;
• Signs of end-organ hypoperfusion: cool, mottled, clammy peripheries, oliguria (urine output below 0.5 mL/kg/hour), altered mental status, raised serum lactate;
• Pulmonary capillary wedge pressure over 18 mmHg when measured — this criterion confirms the cause is cardiac rather than hypovolaemic, and is the single feature that distinguishes cardiogenic shock from other shock states;
• Exclusion of hypovolaemia, sepsis, and other non-cardiac causes as the primary driver.[1]

The clinical importance of cardiogenic shock is its lethality: it complicates roughly 6 to 10 percent of acute MIs, is the leading cause of in-hospital death in MI patients under 75, and — even with modern revascularisation, inotropes and mechanical circulatory support — carries an in-hospital mortality of 40 to 50 percent. The exam skill lies in (1) recognising shock early, before SBP collapses (perfusing organs fail before blood pressure falls — watch lactate, urine output, mentation, skin); (2) distinguishing cardiogenic shock from its mimics (septic, hypovolaemic, obstructive, distributive), because the management is the opposite; (3) identifying the cardiac cause and the reversible subgroup (MI, tamponade, massive PE, mechanical complication, arrhythmia); and (4) running the shock funnel to definitive therapy.[9][13]

Classification — SCAI stages, Forrester subsets, and aetiology

Cardiogenic shock is classified by SCAI staging (the modern prognostic standard), by Forrester haemodynamic subset (the bedside physiological model), and by aetiology (which determines treatment).[1]

SCAI SHOCK stages A to E — the modern prognostic standard

[6]

The SCAI staging was published in 2019 (Baran et al.) and updated in 2022 (Naidu et al.); the B-to-C boundary is the appearance of hypoperfusion (a verbatim concept from the consensus statement), and stages track in-hospital mortality in a steep gradient validated across multiple registries (Jentzer et al., Naidu et al.).[6][7][8]

Forrester subsets — two numbers at the bedside

The older Forrester haemodynamic subsets (Forrester, Diamond, Chatterjee; NEJM 1976) classify the patient at the bedside using two numbers: pulmonary capillary wedge pressure (a proxy for left-sided filling) and cardiac index.[10][11]

• Subset I — warm and dry: wedge below 18 mmHg, CI above 2.2 L/min/m2. Normal perfusion, no congestion. Mortality about 1 percent.
• Subset II — warm and wet: wedge over 18 mmHg, CI above 2.2 L/min/m2. Pulmonary oedema, good peripheral perfusion. Mortality about 10 percent.
• Subset III — cold and dry: wedge below 18 mmHg, CI below 2.2 L/min/m2. Hypoperfusion without congestion — usually relative hypovolaemia; treat with a cautious fluid challenge. Mortality about 20 percent.
• Subset IV — cold and wet: wedge over 18 mmHg, CI below 2.2 L/min/m2. This is classic cardiogenic shock. Mortality about 60 percent untreated.[1]

Aetiology — the classification that drives treatment

The headline categories are: acute MI (LV failure — the commonest), acute mechanical complication of MI (papillary muscle rupture, VSR, free-wall rupture), right ventricular infarction, acute decompensated chronic heart failure or cardiomyopathy, fulminant myocarditis, acute severe valvular disease (MR, AR, MS), arrhythmia (VT, bradyarrhythmia, AF with rapid rate), cardiac tamponade, massive pulmonary embolism (the right ventricle failing against acute afterload), post-cardiotomy shock, drug toxicity (beta-blocker, calcium-channel blocker, digoxin), and rejection of a transplanted heart.[1]

[1]

Epidemiology and risk factors

Cardiogenic shock complicates roughly 6 to 10 percent of acute MIs — down from 8 to 12 percent in the pre-reperfusion era but unchanged over the last two decades despite routine primary PCI, because patients are older and sicker. It is the leading cause of in-hospital death after MI.[1][9]

Demographic and clinical risk factors (the high-yield list):[1]

• Age — patients in shock are on average older (about 65 to 70 years); the SHOCK-trial survival benefit of early revascularisation was confined to those under 75, so age is both a risk factor and a treatment-decision modifier.[2]
• Female sex — women are over-represented in CS-MI cohorts (later presentation, smaller body size, atypical symptoms); the SHOCK trial was roughly one-third female.
• Anterior STEMI — large anterior (especially proximal LAD) infarcts are the single most common infarct location to cause CS, because of the large area of myocardium at risk.
• Large infarct size — peak CK or troponin, LV ejection fraction below 40 percent, wall-motion score index, and lack of collateral circulation or incomplete reperfusion (TIMI flow below 3, no-reflow).
• Prior MI or known LV dysfunction — the second hit on an already-compromised ventricle tips the patient into shock.
• Diabetes mellitus, chronic kidney disease, peripheral arterial disease — common comorbidities that worsen outcome.
• Delay to presentation or reperfusion — every 30-minute delay in door-to-balloon increases 1-year mortality.
• Multivessel coronary disease — supply-side failure; downstream culprit-only versus multivessel PCI is a key decision (CULPRIT-SHOCK).[4]
• Mechanical complications of MI — occur most often on day 3 to 6 post-MI, in patients with smaller infarcts (subendocardial or first MI): papillary muscle rupture (inferior MI — the posteromedial papillary muscle has a single blood supply), ventricular septal rupture, free-wall rupture.[9]

Non-ischaemic causes — fulminant myocarditis (young patients with a recent viral illness, sudden severe LV dysfunction — a high recovery rate if supported); peripartum cardiomyopathy; acute severe valvular regurgitation (endocarditis, traumatic); drug overdose (beta-blocker, calcium-channel blocker, digoxin); advanced cardiomyopathy with a precipitant.[12]

Pathophysiology — the self-perpetuating downward spiral

The pathophysiology of cardiogenic shock is best understood as a self-perpetuating downward spiral in which cardiac dysfunction, neurohormonal activation, systemic inflammation and end-organ failure reinforce one another.[1][13]

1. The initiating insult — pump failure. Acute MI kills roughly 40 percent of the LV myocardium before shock supervenes; loss of functioning muscle reduces stroke volume and cardiac output (CO equals heart rate times stroke volume). When the remaining viable myocardium cannot compensate, cardiac index falls below 2.2 L/min/m2. The same injury — through the Frank-Starling mechanism — raises left ventricular end-diastolic pressure (LVEDP), which transmits back to the left atrium and pulmonary capillaries, raising wedge pressure above 18 mmHg and producing pulmonary congestion and oedema.[10]

2. The vicious spiral — coronary hypoperfusion. Reduced cardiac output lowers diastolic blood pressure and hence coronary perfusion pressure (diastolic BP minus wedge pressure). The subendocardium is most vulnerable (it is perfused in diastole only, against the highest intramyocardial pressure). Worsened subendocardial ischaemia further reduces contractility of the surviving myocardium, which drops stroke volume further — a spiral that terminates in asystole or pulseless electrical activity unless interrupted. This spiral is the biological reason early reperfusion works.[1]

3. Compensatory neurohormonal activation — initially helpful, ultimately harmful. Baroreceptors sense falling blood pressure and activate the sympathetic nervous system (tachycardia, vasoconstriction, increased contractility — raising myocardial oxygen demand in an ischaemic ventricle) and the renin-angiotensin-aldosterone system (vasoconstriction, sodium and water retention). Vasopressin (ADH) rises. These responses initially maintain central organ perfusion, but in established shock they increase afterload, worsen subendocardial ischaemia, and drive further decompensation — the rationale for vasodilator (GTN) and beta-blockade strategies in the chronic phase, and the danger of indiscriminate fluids in the acute phase.[1]

4. The systemic inflammatory response syndrome (SIRS) in CS. In established shock the gut becomes hypoperfused, the endothelium is injured, and a pro-inflammatory cytokine cascade (TNF-alpha, IL-1, IL-6) is released from ischaemic and necrotic myocardium. This produces inducible nitric oxide synthase, excess nitric oxide and peroxynitrite, vasoplegia (pathological vasodilatation on top of pump failure), capillary leak, and myocardial depression — the so-called "septic-like" phenotype of late cardiogenic shock. This is why some CS patients become warm and vasoplegic rather than cold and vasoconstricted, and why noradrenaline rather than dobutamine alone is needed. The NOS inhibitor tilarginine (L-NMMA) was tested in TRIUMPH and failed.[5]

5. End-organ hypoperfusion — the clinical face of CS.[1]

• Kidney — falling renal perfusion activates tubuloglomerular feedback, dropping GFR; oliguria (under 0.5 mL/kg/hour) is one of the earliest bedside signs; type 1 cardiorenal syndrome and acute tubular necrosis follow.
• Brain — confusion, agitation, obtundation.
• Liver — ischaemic hepatitis ("shock liver") with transaminases over 1000 IU/L and centrilobular necrosis; cardiac cirrhosis in chronic congestion.
• Gut — hypoperfusion, bacterial translocation, ileus; mesenteric ischaemia in extreme cases.
• Skin — cool, clammy, mottled, delayed capillary refill (over 2 seconds) — vasoconstriction shunts blood to vital organs.
• Skeletal muscle — lactic acidosis from anaerobic metabolism; lactate above 2 mmol/L (and rising) is a marker of severity and a target of therapy.[1]

6. The role of the right ventricle. RV infarction (with inferior MI) is a special pathophysiology: the dilated, failing RV causes systemic venous congestion (raised JVP, hepatomegaly) with clear lung fields (the LV is underfilled because the RV cannot deliver preload), and hypotension that is exquisitely preload-sensitive — nitrates, diuretics and beta-blockers precipitate collapse; volume challenge and reperfusion are the answer. RV failure on top of LV failure (biventricular CS) is the most lethal phenotype and demands biventricular mechanical support (VA-ECMO rather than isolated LV assist).[1]

7. The macro- and microcirculation dissociate. In late CS, macro-haemodynamics may improve on inotropes while the microcirculation remains failed — the so-called "lost in translation" phenomenon. This underlies the search for microcirculatory monitoring (sublingual SDF imaging) and the failure of pure pressure-based endpoints.[13]

Clinical presentation — hypoperfusion plus congestion plus a cardiac cause

The clinical face of cardiogenic shock is the triad of hypoperfusion plus congestion plus a cardiac cause.[13]

Symptoms (the patient is usually too sick to give a long history):[1]

• Cardiac symptoms of the underlying cause — chest pain of acute MI (crushing central, radiation to arm or jaw, autonomic features), palpitation (VT, AF), syncope (arrhythmia, PE, tamponade), the breathlessness of pulmonary oedema.
• Hypoperfusion symptoms — dizziness, light-headedness, syncope, fatigue, confusion, oliguria or anuria, cold extremities.
• Pulmonary congestion — orthopnoea, paroxysmal nocturnal dyspnoea, frothy pink sputum (frank pulmonary oedema) — unless the cause is RV infarct, massive PE, or tamponade, in which case the lungs are clear despite shock.[1]

Vital signs (the first clue):[1]

• Hypotension — SBP below 90 mmHg, or MAP below 65 mmHg, or a fall of more than 30 mmHg from baseline, or only sustained on inotropes or vasopressors. A normal BP does not exclude shock — compensatory vasoconstriction can mask hypoperfusion; assess perfusion, not pressure.
• Tachycardia — compensatory (under 100 is a sinister sign — severe pump failure or conduction disease or AV block).
• Tachypnoea — from pulmonary oedema, metabolic acidosis (Kussmaul breathing), or anxiety.
• Hypoxaemia — pulmonary oedema, V/Q mismatch.
• Cool peripheries, delayed capillary refill (over 2 s), mottled skin — vasoconstriction. But in late, vasoplegic shock the skin may be warm (NO-mediated).
• Oliguria — catheterise early; urine output under 0.5 mL/kg/hour.
• Altered mental status — confusion, agitation, obtundation.[1]

Examination (organ by organ):[1]

• JVP — typically raised (biventricular failure, RV infarct, tamponade, PE); a flat JVP suggests hypovolaemia or vasodilatory shock and prompts a fluid challenge.
• Precordium — a diffuse, weak apex (LV failure); an RV heave (RV infarct, PE, pulmonary hypertension); a right parasternal heave in massive PE; an absent apex with muffled sounds in tamponade.
• Auscultation — an S3 gallop (the auscultatory hallmark of severe LV failure), bibasal crackles (pulmonary oedema), a new pansystolic murmur at the apex radiating to the axilla (papillary muscle rupture — acute severe MR) or at the lower left sternal edge with a thrill (VSR); a diastolic murmur of acute severe AR (dissection, endocarditis); a pericardial rub (tamponade or myopericarditis); a silent precordium (a large effusion or tamponade, cardiac arrest).
• Abdomen — tender pulsatile hepatomegaly with hepatojugular reflux (right-heart failure).
• Periphery — cool, clammy, mottled, peripheral cyanosis; a weak and thready pulse; a narrow pulse pressure (low stroke volume).[1]

Atypical presentations (high-yield)

• Elderly or diabetic — a painless MI with confusion, falls, breathlessness, fatigue as the only clues; shock may be the first sign of infarction.
• Right ventricular infarction (with inferior MI) — the clear-lung-fields shock: raised JVP, hypotension, a Kussmaul sign (the JVP rises paradoxically with inspiration), a clear chest; worsens catastrophically with nitrates or diuretics.[9]
• Mechanical complication at day 3 to 6 post-MI — a sudden new murmur with haemodynamic collapse in a patient who had been recovering; papillary muscle rupture (pansystolic apical, often no thrill because LA pressure equalises with LV) or ventricular septal rupture (a loud pansystolic lower-left-sternal-edge murmur with a thrill).
• Cardiac tamponade — Beck triad (hypotension, raised JVP, muffled heart sounds), pulsus paradoxus (a drop in SBP over 10 mmHg on inspiration), electrical alternans on ECG; emergency pericardiocentesis.
• Massive pulmonary embolism — sudden syncope, pleuritic pain, a right-heart failure pattern on ECG (S1Q3T3, right-axis deviation, T-wave inversion V1 to V3, RBBB), hypoxaemia with a clear CXR; right ventricular strain on echo.
• Drug overdose (beta-blocker, calcium-channel blocker, digoxin) — bradycardia in shock is the clue; specific antidotes (glucagon, high-dose insulin euglycaemic therapy, digoxin Fab, calcium, lipid emulsion).[1]

The differential — separate cardiogenic from its mimics, because the treatment is opposite

The first task is to separate cardiogenic shock from its mimics, because the management is the opposite (cardiogenic needs an inotrope, a vasopressor and decongestion; hypovolaemic and distributive need fluid; obstructive needs a needle or treatment of the obstruction).[13]

• Hypovolaemic shock — blood loss (GI bleed, trauma, ruptured AAA, postpartum haemorrhage), fluid loss (vomiting, diarrhoea, burns). Distinguish: a flat JVP, dry peripheries initially then cold, wedge below 18 mmHg, high SVR, no chest pain. Treat with balanced crystalloid 30 mL/kg then blood if bleeding.
• Septic or distributive shock — infection, warm peripheries early (vasodilatation), wedge normal or low, high cardiac output (until late), SVR low, often a leucocytosis and a source. Treat with fluids, antibiotics within 1 hour, noradrenaline, source control. A common pitfall: late sepsis can become cold with low-output myocardial depression, mimicking CS — the bedside echo (looking for a primary cardiac problem) and the wedge help.
• Obstructive shock — massive PE, tension pneumothorax, cardiac tamponade. Each is immediately reversible:
  • Tamponade — Beck triad, pulsus paradoxus, equalisation of diastolic pressures, a swinging heart on echo; pericardiocentesis.
  • Tension pneumothorax — tracheal deviation, hyper-resonance, absent breath sounds on one side; needle decompression (5th intercostal space, mid-axillary line) then a chest drain.
  • Massive PE — sudden syncope, RV strain on ECG and echo, raised D-dimer, CT pulmonary angiogram; systemic thrombolysis (alteplase 100 mg over 2 hours) or catheter-directed thrombolysis or embolectomy.
• Anaphylactic shock — exposure, urticaria, angioedema, bronchospasm, hypotension within minutes; treat with IM adrenaline 0.5 mg (0.5 mL of 1 in 1000), IV fluids, chlorphenamine, hydrocortisone.
• Acute adrenal crisis (Addisonian crisis) — weakness, abdominal pain, hyponatraemia, hyperkalaemia, hypoglycaemia, pigmentation; treat with IV hydrocortisone 100 mg and fluids.
• Cardiogenic mimics of shock — severe aortic stenosis with low-output failure, hypertrophic obstructive cardiomyopathy (LVOT obstruction, worsened by inotropes and diuresis — beware), severe acidosis, drug overdose.[1]

The single best discriminator is the bedside echocardiogram combined with wedge pressure or cardiac index measurement (where available) — a globally hypokinetic, dilated LV with raised wedge and low CI confirms cardiogenic shock; a normal LV with low wedge points to hypovolaemia; a dilated RV with raised JVP and clear lungs points to RV infarct or PE.[1]

Bedside assessment — perfusion, not pressure

ABCDE first. Cardiogenic shock is a perfusion diagnosis, so assess perfusion, not just pressure:[13]

Bedside perfusion assessment (the earliest signs):[1]

• Capillary refill time (press the sternum or a finger pad for 5 s, release) — delayed if over 2 seconds; mottled skin in advanced shock.
• Urine output — catheterise early; oliguria under 0.5 mL/kg/hour is one of the earliest signs of failing renal perfusion, preceding a BP fall.
• Mental status — confusion, agitation, obtundation.
• Lactate — arterial or venous; over 2 mmol/L is raised, over 4 mmol/L severe; a rising lactate despite therapy is a marker of failure to resuscitate.
• Skin temperature — cool peripheries (cold shock) versus warm (vasoplegic late shock).[1]

JVP assessment at 45 degrees: raised in CS (biventricular failure, RV infarct, PE, tamponade); a flat JVP challenges the diagnosis and prompts a cautious fluid challenge.[1]

Pulsus paradoxus — a drop in SBP over 10 mmHg on inspiration — points to tamponade, severe asthma or COPD, tension pneumothorax, massive PE.[1]

The "shock bundle" at the bedside (the National Cardiogenic Shock Initiative or Tehrani et al. 2020 protocol):[13]

1. Arterial line (continuous BP) — the brachial or femoral route; the radial under-reads in severe vasoconstriction.
2. Two large-bore IV cannulae and central venous access (right internal jugular or femoral, given the need for a PA catheter and possible ECMO cannulation).
3. Bedside echo within minutes — confirm the cardiac cause, identify mechanical complications, RV function, valve lesions, effusion or tamponade.
4. Pulmonary artery (Swan-Ganz) catheter — for the deteriorating or vasopressor-dependent patient: gives wedge, cardiac output (thermodilution), mixed venous saturation (SvO2), and calculates cardiac power output (CPO equals MAP times CO over 451, in Watts). CPO below 0.6 W is the most powerful single haemodynamic predictor of mortality in CS.
5. Lactate, ABG, full blood count, U and E, LFT, troponin, BNP or NT-proBNP, group-and-save, cross-match, coagulation — baseline labs.
6. ECG — STEMI (drive to emergency PCI), tachy or bradyarrhythmia, a PE pattern, tamponade (electrical alternans).
7. CXR — pulmonary oedema, cardiomegaly, a widened mediastinum (dissection), pneumothorax.[1]

Investigations — echo is the test; haemodynamics confirm

First-line (in parallel with resuscitation):[9][13]

• 12-lead ECG — STEMI drives emergency revascularisation (door-to-balloon within 90 min); ST elevation in II, III or aVF with V4R suggests RV infarct; S1Q3T3, right-axis deviation, RBBB, T-wave inversion V1 to V3 suggests massive PE; electrical alternans suggests tamponade; a wide QRS or hyperkalaemia — beware acidosis-induced arrhythmia.
• Chest X-ray — pulmonary oedema (Bat's-wing alveolar shadowing, Kerley B lines, cardiomegaly, pleural effusions); clear lung fields with shock suggest RV infarct, PE, tamponade, hypovolaemia.
• Echocardiography (transthoracic, emergency bedside) — the single most important diagnostic test. Look for: global LV hypokinesis (large MI, myocarditis, cardiomyopathy), regional wall-motion abnormality in a coronary distribution (acute MI), a dilated failing RV with preserved LV (RV infarct, massive PE), severe MR with a flail leaflet (papillary muscle rupture), a ventricular septal defect with a high-velocity left-to-right jet on colour Doppler (VSR), a pericardial effusion with diastolic RV collapse and a swinging heart (tamponade), regional wall-motion abnormality of the aortic valve (acute severe AR), an LV apical thrombus. Echo also estimates LVEF and pulmonary artery systolic pressure (the TR jet).
• Arterial blood gas — metabolic acidosis (low pH, low bicarbonate, raised lactate), hypoxaemia, a raised base deficit (correlates with lactate and outcome).
• Lactate — arterial or venous; clearance is a target of therapy (failing to clear lactate is an indication to escalate).
• Troponin — confirms myocardial injury (but may already be high in chronic HF or renal failure; trend the rise).
• BNP or NT-proBNP — high in CS (a cardiac cause); a low BNP argues against a cardiac cause.
• Renal function, electrolytes, liver function, coagulation, full blood count — baseline and end-organ function.
• Drug levels — digoxin, salicylate, paracetamol (an overdose screen), beta-blocker or CCB (history).[1]

Invasive haemodynamics (PA catheter) — for the deteriorating or refractory patient:[10][13]

• Pulmonary capillary wedge pressure (PCWP) — over 18 mmHg in cardiogenic shock (the defining haemodynamic criterion; below 18 mmHg with a low CI is "Forrester III — cold and dry" and should prompt a cautious fluid challenge rather than a diuretic).
• Cardiac index (CI) — below 2.2 L/min/m2 in CS.
• Mixed venous saturation (SvO2) — below 65 percent indicates inadequate oxygen delivery; the goal is 70 percent.
• Systemic vascular resistance (SVR) — typically high (compensatory vasoconstriction) in early CS, low in vasoplegic late CS.
• Cardiac Power Output (CPO) equals (MAP times CO) over 451 (in Watts) — CPO below 0.6 W identifies severe CS and is the strongest single haemodynamic predictor of mortality.[7]

Coronary angiography — mandatory in MI-related CS; it identifies the culprit lesion, drives immediate revascularisation (culprit-lesion-only PCI per CULPRIT-SHOCK), and identifies the surgical or mechanical problem.[4]

Advanced (case by case): CT coronary angiography (if a non-ischaemic cause is suspected and the patient is stable enough), cardiac MRI (myocarditis, cardiomyopathy, infiltrative disease — usually once stabilised), CT pulmonary angiogram (massive PE), endomyocardial biopsy (giant-cell myocarditis, sarcoidosis, transplant rejection), a drug screen (overdose).[1]

Named scores and criteria — reproduced verbatim

SCAI SHOCK stages (Baran 2019, Naidu 2022)[6][7]

[1]

The B-to-C boundary is the appearance of overt hypoperfusion.[1]

Forrester haemodynamic subsets (Forrester, Diamond, Chatterjee; NEJM 1976)[10][11]

[1]

SHOCK trial entry criteria (Hochman 1999)[1]

• SBP below 90 mmHg for at least 30 minutes OR requiring inotropes or vasopressors to maintain SBP at least 90 mmHg;
• CI below 2.2 L/min/m2 AND PCWP over 15 mmHg (the original trial used 15);
• plus clinically evident hypoperfusion (oliguria, cold peripheries, altered mentation).[1]

[1]

Resuscitation — the shock funnel begins

[1]

ABCDE first, in parallel with the diagnostic work-up. Cardiogenic shock is a time-critical emergency — every minute of hypoperfusion deepens the spiral.[9][13]

Airway and breathing:[1]

• High-flow oxygen to target SpO2 94 to 98 percent (88 to 92 percent in COPD or CO2 retainers); escalate to high-flow nasal cannula or non-invasive ventilation (CPAP or BiPAP) for pulmonary oedema — NIV reduces the work of breathing, recruits alveoli and lowers preload and afterload.
• Intubate and mechanically ventilate if the patient is tiring, comatose, or in cardiac arrest — positive-pressure ventilation also reduces LV afterload (a useful haemodynamic effect in CS) but reduces venous return, so titrate carefully and ensure adequate preload.[1]

Circulation — early vascular access and monitoring:[1]

• Two large-bore cannulae, an arterial line (continuous BP — the radial under-reads in vasoconstriction), a central venous line (right IJ preferred, leave the femoral for possible ECMO), a urinary catheter.
• A PA catheter for the deteriorating, vasopressor-dependent, or MCS-considered patient.
• A fluid challenge only if hypovolaemic or the wedge is below 15 mmHg — 250 mL balanced crystalloid over 10 minutes, reassess; avoid fluid overload in CS with a raised wedge (it worsens pulmonary oedema and RV strain).[1]

Circulation — pharmacological haemodynamic support (the core of early therapy):[13]

The goal is MAP at least 65 mmHg and CI at least 2.2 L/min/m2 while preserving coronary perfusion, without worsened arrhythmia or ischaemia. The choice of agent depends on the haemodynamic phenotype:[1]

• Cold, hypotensive CS (low CI, low MAP, raised wedge — the classic form) — start an inotrope to raise CI and a vasopressor to defend MAP:

  • Dobutamine 2 to 20 micrograms/kg/min IV — a beta-1 agonist; a positive inotrope and chronotrope; raises CO but also myocardial oxygen demand and may worsen ischaemia and arrhythmia; tachyphylaxis; the first-line inotrope in most CS. Titrated to CI and lactate.
  • Milrinone 0.125 to 0.75 micrograms/kg/min IV (loading 50 micrograms/kg over 10 min) — a PDE-3 inhibitor, an "inodilator" (inotropy plus vasodilatation); preferred when pulmonary hypertension or RV failure coexist, and in beta-blocker-related CS; the vasodilator effect may worsen hypotension — combine with a vasopressor.
  • Levosimendan — a calcium-sensitiser (an inodilator without raising intracellular calcium); loading 6 to 12 micrograms/kg over 10 min then 0.05 to 0.2 micrograms/kg/min; used in Europe for refractory CS, especially post-cardiotomy and takotsubo; can cause hypotension.
  • Noradrenaline 0.05 to 1 microgram/kg/min IV — an alpha and beta-1 agonist; the preferred first-line vasopressor in CS (a more potent vasoconstrictor than dopamine, with fewer arrhythmias); titrate to MAP at least 65 mmHg.
  • Adrenaline 0.05 to 1 microgram/kg/min IV — for severe or refractory CS; a powerful inotrope and vasoconstrictor; raises lactate (anaerobic skeletal-muscle glycolysis) — confounds lactate monitoring; a high arrhythmia risk.
  • Vasopressin 0.01 to 0.04 units/min IV — catecholamine-sparing; useful in vasoplegic late CS or beta-blocker or CCB overdose.[1]

• Warm vasoplegic CS (low SVR despite an inotrope — the late, SIRS-like phenotype) — noradrenaline first-line, add vasopressin if catecholamine-resistant; consider steroids (hydrocortisone 200 mg/day) in refractory vasoplegia (controversial).[1]

• Dopamine (2 to 20 micrograms/kg/min) — no longer recommended as first-line in CS: the SOAP-II trial showed more arrhythmia and higher mortality than noradrenaline in cardiogenic shock; reserve for symptomatic bradycardia where pacing is not available.[13]

The "shock funnel" — escalation triggers: escalate when the patient is SCAI stage D or E, has a rising lactate despite an inotrope, worsening end-organ function, high inotrope or vasopressor doses, or cardiac arrest or peri-arrest.[13]

Adjunctive therapy in MI-related CS:[9]

• Dual antiplatelet therapy — aspirin 300 mg loading then 75 mg daily; a P2Y12 inhibitor — ticagrelor 180 mg loading then 90 mg twice daily (preferred in CS-PCI; non-competitive, fast onset), prasugrel 60 mg loading then 10 mg daily (avoid in stroke history, age over 75, weight under 60 kg), or clopidogrel 600 mg loading then 75 mg daily (if high bleeding risk).
• Parenteral anticoagulation — unfractionated heparin (preferred in CS for rapid reversibility and renal-independent clearance); bivalirudin in heparin-induced thrombocytopenia.
• Statins — atorvastatin 80 mg high-intensity.
• Glycaemic control — maintain glucose 7.8 to 10 mmol/L (avoid hypoglycaemia; tight control is harmful in CS).
• Revascularisation — see Definitive Management.[1]

Definitive management — cause-specific, team-based, escalate to MCS

The definitive management of CS is cause-specific and team-based: identify and treat the cardiac cause, support the circulation to break the spiral, and escalate to mechanical circulatory support (MCS) as a bridge to recovery, decision, transplant or durable LVAD.[1][13]

Step 1 — Identify and treat the cause (within minutes to hours)

The single biggest mortality-reducing intervention in MI-CS is early coronary revascularisation.[1]

• STEMI-CS — primary PCI within 90 minutes of first medical contact (door-to-balloon), the gold standard; if PCI is unavailable within 120 minutes, fibrinolysis (alteplase or tenecteplase, weight-based) — but fibrinolysis is less effective in shock and carries bleeding risk.
• NSTEMI-CS — an immediate invasive strategy (within 2 hours) with PCI.
• CULPRIT-lesion-only PCI is preferred over multivessel PCI in MI-CS (the CULPRIT-SHOCK trial, Thiele 2017): culprit-lesion-only PCI reduced the composite of death OR severe renal failure needing RRT (45.9 percent versus 55.4 percent; relative risk 0.83, P equal to 0.01) compared with immediate multivessel PCI. Staged complete revascularisation is performed later once stabilised.[4]
• Mechanical complications of MI — emergency surgical repair for papillary muscle rupture, VSR, free-wall rupture (and for severe ischaemic MR not amenable to PCI); these are surgical emergencies, with MCS as a bridge to surgery.
• Acute severe valvular disease — emergency valve surgery (acute severe MR, AR, MS).
• Cardiac tamponade — emergency pericardiocentesis (subxiphoid, echo-guided).
• Massive PE — systemic thrombolysis (alteplase 100 mg over 2 hours) or catheter-directed thrombolysis or surgical embolectomy.
• Arrhythmia — DC cardioversion if an unstable tachyarrhythmia; temporary then permanent pacing for symptomatic bradyarrhythmia or AV block; amiodarone 300 mg over 1 hour then 900 mg over 24 hours for stable VT.
• Drug overdose — beta-blocker: glucagon 5 to 10 mg IV bolus then an infusion 1 to 5 mg/hour, high-dose insulin euglycaemic therapy (1 unit/kg bolus then 0.5 to 1 unit/kg/hour with dextrose), lipid emulsion in refractory cases; calcium-channel blocker: calcium chloride 10 percent 10 to 20 mL or calcium gluconate, high-dose insulin, lipid emulsion; digoxin: digoxin-specific Fab antibody fragments (DigiFab) dose based on serum level or amount ingested.
• Fulminant myocarditis — supportive MCS (often VA-ECMO) with or without IV corticosteroids and immunosuppression in giant-cell or autoimmune forms; a high recovery rate if supported through the acute phase.
• End-stage cardiomyopathy or transplant rejection — an MCS bridge to transplant or a palliative pathway.[1]

Step 2 — Mechanical circulatory support (MCS) — bridge to recovery or decision

MCS unloads the failing ventricle, restores end-organ perfusion, and buys time for definitive therapy. It is not a destination for most (post-cardiotomy support being the exception).[13]

[13]

The choice of MCS depends on the primary failing chamber, the oxygenation need, the anticipated duration, and the centre expertise. A practical algorithm: LV-dominant CS — Impella (or IABP if Impella is unavailable); RV-dominant or biventricular CS, or CS with hypoxaemia or arrest — VA-ECMO; combine (ECMO plus Impella equals "ECPELLA") when LV distension is a problem.[13]

Step 3 — Decongestion, oxygen delivery and metabolic support

• Diuresis — furosemide 20 to 80 mg IV bolus (or a continuous infusion 5 to 20 mg/hour for diuretic-resistant) to bring wedge toward 18 mmHg once MAP is defended; cautious in RV infarct (preload-dependent).
• Ventilation — see Resuscitation; NIV for pulmonary oedema, invasive ventilation for the tiring or comatose patient.
• Correct electrolytes and acidosis — potassium to 4 to 4.5 mmol/L, magnesium at least 1 mmol/L (arrhythmia prevention); renal replacement therapy for severe acidosis (pH below 7.1), hyperkalaemia, or fluid overload unresponsive to diuretics.
• Glucose 7.8 to 10 mmol/L, haemoglobin at least 80 to 90 g/L (controversial — too aggressive transfusion worsens outcome; the TRICC-equivalent principle applies), thromboprophylaxis (LMWH unless contraindicated), stress-ulcer prophylaxis, early enteral nutrition once stable.[1]

Step 4 — De-escalation and disposition

• Wean MCS and inotropes as the underlying cause recovers — guided by lactate clearance, CI, CPO, and echocardiographic recovery of EF. Wean VA-ECMO by reducing the sweep gas and then the flow over hours; decannulate surgically.
• Long-term HF therapy — once euvolaemic and stable, introduce the four pillars of HFrEF (ARNI or ACE-inhibitor, beta-blocker, MRA, SGLT2 inhibitor) cautiously and uptitrate.
• Bridge to transplantation or durable LVAD for those who cannot wean (end-stage cardiomyopathy); a palliative pathway for those who are not candidates.[1]

Special situations you will actually meet

• Acute MI with LV failure (the commonest CS) — typically a large anterior STEMI; primary PCI within 90 min; inotrope plus noradrenaline plus MCS as a bridge; culprit-lesion-only PCI.[1][4]
• Right ventricular infarction (with inferior STEMI) — the clear-lung-fields shock; a raised JVP with a Kussmaul sign, hypotension, a clear chest. Volume challenge (250 mL boluses to a target of a raised JVP without pulmonary oedema — the RV is preload-dependent); avoid nitrates, diuretics, beta-blockers; reperfusion (PCI of the RCA); dobutamine if hypotension persists despite adequate preload; maintain AV synchrony (atrial infarct and AV block are common — consider atrioventricular sequential pacing). An inotrope and a diuretic inappropriately given for 'pulmonary oedema' that is actually RV infarct is a classic fatal error.[9]
• Acute mechanical complications of MI (day 3 to 6 post-MI) — a sudden haemodynamic collapse with a new murmur:
  • Papillary muscle rupture — the posteromedial papillary muscle (a single blood supply from the PDA) in inferior MI; acute severe MR, a pansystolic apical murmur (may be soft if LA pressure equalises with LV), pulmonary oedema, shock. Echo shows a flail leaflet and an eccentric MR jet. Emergency surgery (MV repair or replacement); IABP or Impella as a bridge; a vasodilator (nitroprusside) to reduce afterload if BP tolerates.
  • Ventricular septal rupture — a loud pansystolic murmur at the lower left sternal edge with a thrill, biventricular failure. Echo with colour Doppler shows a left-to-right shunt. Emergency surgical closure (or a percutaneous device in selected cases); MCS as a bridge.
  • Free-wall rupture — sudden chest pain, pericardial tamponade, electromechanical dissociation, usually fatal; emergency surgery if recognised.[9]
• Fulminant myocarditis — a young patient, a viral prodrome, sudden severe LV dysfunction with or without arrhythmia and AV block. VA-ECMO support through the acute phase; IV corticosteroids and immunosuppression for giant-cell, eosinophilic, or biopsy-proven autoimmune myocarditis; a high recovery rate (over 70 percent survival if supported). Consider endomyocardial biopsy if giant-cell is suspected (a poor prognosis without immunosuppression).
• Acute decompensated heart failure or end-stage cardiomyopathy — chronic HF with a precipitant (ischaemia, arrhythmia, infection, anaemia, an NSAID, non-adherence); treat the precipitant and decongest, do not start or uptitrate a beta-blocker until euvolaemic; consider MCS or transplant.
• Acute severe valvular disease — acute severe MR (papillary muscle rupture, endocarditis, trauma), acute severe AR (aortic dissection, endocarditis), acute severe MS (rare, thrombosis of a prosthetic valve). Emergency valve surgery.[1]
• Massive pulmonary embolism — sudden syncope, RV strain on ECG and echo, hypoxaemia with a clear CXR, raised D-dimer, confirmed on CTPA. Systemic thrombolysis (alteplase 100 mg over 2 hours) if haemodynamically unstable; catheter-directed thrombolysis or surgical embolectomy if there is a contraindication or failure.
• Cardiac tamponade — Beck triad, pulsus paradoxus, electrical alternans, diastolic RV or RA collapse on echo. Emergency pericardiocentesis (subxiphoid, echo-guided); treat the cause (malignancy, uraemia, infection, post-procedural, autoimmune).
• Drug overdose — beta-blocker: glucagon plus high-dose insulin plus lipid emulsion plus MCS; calcium-channel blocker: calcium plus high-dose insulin plus lipid emulsion; digoxin: DigiFab. Beware: standard inotropes often fail; MCS (VA-ECMO) may be needed as a bridge.
• Post-cardiotomy shock — failure to wean from cardiopulmonary bypass; CentriMag or VA-ECMO support; a high mortality (over 50 percent).
• Takotsubo cardiomyopathy — stress-induced apical ballooning; may present with shock and LVOT obstruction — beware inotropes (they worsen LVOT obstruction); treat with a beta-blocker and careful fluid, MCS if refractory.
• Pregnancy-related CS — peripartum cardiomyopathy (HF with EF below 45 percent in the last month of pregnancy to 5 months postpartum); avoid teratogenic drugs in pregnancy (ACE-inhibitor, ARB, MRA), use hydralazine-nitrate; bromocriptine 2.5 mg twice daily for 8 weeks (stop breastfeeding); anticoagulate if EF below 30 percent; a high recovery rate (50 to 70 percent).[12]

How patients with cardiogenic shock come to harm (the preventable list)

• Treating CS as if it were septic or hypovolaemic shock — flooding a high-wedge patient with fluid causes flash pulmonary oedema and RV strain. Always check the wedge, the JVP and the echo before fluids.[1]
• Failing to recognise RV infarct — giving nitrates, diuretics or beta-blockers to a preload-dependent RV infarct causes catastrophic collapse.[9]
• Delaying revascularisation for investigations — every minute of delay deepens the spiral; the SHOCK trial is the proof.[1]
• Using dopamine as the first-line inotrope — SOAP-II showed more arrhythmia and higher mortality than noradrenaline; dobutamine (or milrinone) plus noradrenaline is the modern combination.[13]
• Relying on blood pressure alone — perfusion fails before pressure; monitor lactate, urine output, mentation, skin.[6]
• Misclassifying a mechanical complication as "worsening LV failure" — a new murmur post-MI is papillary muscle rupture or VSR until proven otherwise; urgent echo.[9]
• Forgetting the differential of shock — tamponade, tension pneumothorax, massive PE, anaphylaxis, adrenal crisis are all immediately reversible; missing them is fatal.[1]
• Indiscriminate IABP use after IABP-SHOCK II — routine IABP does NOT improve mortality; reserve for selected cases.[3]
• Giving fluids or inotropes in HOCM-induced shock — worsens LVOT obstruction; use a beta-blocker and fluid instead.[1]
• Over-transfusion aiming for a high haemoglobin — worsens afterload and mortality in CS; target 80 to 90 g/L.[1]

Prognosis and disposition

In-hospital mortality of CS remains 40 to 50 percent despite modern care, and over 80 percent for SCAI stage E. One-year mortality approaches 60 to 70 percent in MI-CS without revascularisation, halved by early revascularisation.[1][2]

Predictors of poor outcome: older age (especially over 75), lower EF, lower cardiac index, lower CPO (below 0.6 W), higher wedge, rising lactate, renal dysfunction, hyperlactataemia not clearing, biventricular failure, mechanical complications, delay to revascularisation, out-of-hospital cardiac arrest, SCAI stage D or E at presentation, multi-organ failure.[7][8]

Disposition:[1]

• All CS patients belong in a critical-care environment (a cardiac ICU or coronary care unit with MCS capability) with invasive monitoring and rapid access to PCI, surgery and MCS.
• Early transfer to a regional shock centre for the deteriorating patient or for MCS or transplant consideration.
• Survivors need lifelong cardiology follow-up — GDMT for HFrEF, device therapy (ICD or CRT) once stable, secondary prevention, cardiac rehabilitation, and a palliative-care discussion for the non-recoverable, non-transplant candidate.[1]

Pregnancy and special populations

• Elderly (over 75) — atypical presentation, higher mortality; the SHOCK-trial benefit of early revascularisation did not extend to over-75 in the original analysis (decision-making with the patient and family); nevertheless revascularisation is offered if meaningful survival is plausible.
• Pregnancy — peripartum cardiomyopathy (last month of pregnancy to 5 months postpartum) — avoid teratogenic drugs in pregnancy (ACE-inhibitor, ARB, MRA); use hydralazine-nitrate, a beta-blocker (metoprolol), furosemide; bromocriptine postpartum; anticoagulate if EF below 30 percent; a high recovery rate. Massive peripartum PE, amniotic-fluid embolism are other causes of CS in pregnancy. Use a left-lateral tilt to relieve aortocaval compression. Multidisciplinary obstetric-cardiology-anaesthetic care.[12]
• Children or paediatric CS — usually viral myocarditis, congenital heart disease (post-operative or uncorrected), cardiomyopathy, arrhythmia, sepsis. Weight-based dosing of all drugs; VA-ECMO is the dominant MCS; heart transplantation for end-stage disease.
• Diabetic — a silent MI, worse microvascular disease, a higher risk of CS and worse outcome; manage glucose 7.8 to 10 mmol/L.
• Chronic kidney disease — adjust drug doses; contrast during PCI — weigh the risk-benefit; renal replacement therapy for severe AKI; prevent contrast-induced nephropathy with isotonic saline.
• Anticoagulated patient on warfarin or a DOAC — reverse before emergency PCI or surgery (vitamin K plus PCC or FFP for warfarin; specific antidotes — andexanet for apixaban or rivaroxaban, idarucizumab for dabigatran; PCC for other DOACs).
• Post-cardiac-arrest — targeted temperature management (32 to 36 degrees C for 24 hours) if comatose after ROSC; CS in this setting carries a very high mortality; early revascularisation if STEMI.
• Immunocompromised or transplant patient — transplant rejection, drug cardiotoxicity, opportunistic myocarditis; endomyocardial biopsy if rejection is suspected.[1]

Evidence, guidelines and regional differences

Key guidelines: the 2023 ESC ACS Guidelines (Byrne et al.) for the acute MI-CS pathway (early revascularisation, culprit-lesion-only PCI); the 2022 AHA/ACC/HFSA Heart Failure Guideline (Heidenreich et al.) for HF-CS; the SCAI SHOCK classification (Baran 2019, Naidu 2022) for staging; the National Cardiogenic Shock Initiative standardised protocol (Tehrani et al., JACC:HF 2020) for the shock funnel.[6][7][9][12][13]

Landmark trials and statements every exam candidate must know:[1]

• SHOCK trial (Hochman et al., NEJM 1999) — randomised early revascularisation (PCI or CABG within 48 hours) versus initial medical stabilisation in MI-CS. Early revascularisation did NOT significantly reduce 30-day all-cause mortality (46.7 percent versus 56.0 percent, P equal to 0.11) but DID reduce 6-month mortality (50.3 percent versus 63.1 percent, P equal to 0.027) — cite it for the 6-month and 1-year survival benefit, NOT for a 30-day mortality win.[1]
• SHOCK 1-year follow-up (Hochman et al., JAMA 2001) — 1-year survival 46.7 percent versus 33.6 percent (P under 0.03), with the benefit confined to age under 75. This trial established early revascularisation as the standard of care in MI-CS.[2]
• IABP-SHOCK II (Thiele et al., NEJM 2012) — routine IABP in MI-CS did NOT reduce 30-day mortality (39.7 percent versus 41.3 percent, P equal to 0.69) — the basis for demoting routine IABP from Class I to Class IIa or III. The IABP retained a role in selected mechanical-complication cases.[3]
• CULPRIT-SHOCK (Thiele et al., NEJM 2017) — in MI-CS with multivessel disease, culprit-lesion-only PCI reduced the composite of death OR severe renal failure needing RRT (45.9 percent versus 55.4 percent; RR 0.83, P equal to 0.01). Death alone RR 0.84 (P equal to 0.03); RRT alone RR 0.71 (P equal to 0.07, not significant). Cite the composite. Multivessel PCI is deferred to a staged procedure.[4]
• TRIUMPH (Alexander et al., JAMA 2007) — the NOS inhibitor tilarginine (L-NMMA) in MI-CS did NOT reduce mortality and trended toward harm; the trial was stopped early for futility. A landmark negative trial — targeted NO modulation in CS does not work.[5]
• SOAP-II (De Backer et al., NEJM 2010) — dopamine versus noradrenaline in shock: more arrhythmic events with dopamine and a trend to higher mortality in the cardiogenic subgroup — the basis for noradrenaline as the preferred first-line vasopressor in CS (referenced in the SCAI update).[13]
• SCAI 2019 (Baran et al.) and 2022 update (Naidu et al.) — the 5-stage classification (A to E) with the B-to-C boundary defined by the appearance of hypoperfusion; validated against in-hospital mortality across registries (Jentzer 2019, Naidu 2022).[6][7][8]

Regional deltas:[1]

• US (SCAI or AHA) — SCAI SHOCK staging drives triage; early revascularisation in MI-CS is Class I; culprit-lesion-only PCI (CULPRIT-SHOCK adopted); Impella and VA-ECMO at tertiary shock centres; the National Cardiogenic Shock Initiative standardised protocol.
• UK (NICE or NHS England) — a developing national CS network with regional shock centres, ECMO retrieval; routine IABP use declined post-IABP-SHOCK II; early revascularisation via cardiac networks.
• Europe (ESC) — the 2023 ESC ACS Guidelines endorse early revascularisation and culprit-only PCI; levosimendan is used in some countries for refractory CS.
• India (NEET-PG or INICET context) — primary PCI is not universally available within 90 minutes; fibrinolysis (streptokinase historically, now tenecteplase) remains common as first reperfusion; delayed presentation is typical (mean 6 to 12 hours); resource limits constrain PA catheter, Impella and VA-ECMO availability — concentrated in tertiary centres; a high prevalence of rheumatic valvular disease and cardiomyopathy as non-MI causes; cost-benefit discussions with the family are central; dobutamine and noradrenaline are widely available and affordable.[1]

Current controversies: (1) the optimal MCS choice (Impella versus VA-ECMO versus ECPELLA — the RECOVER IV, DANGER SHOCK, ECLS-SHOCK trials); (2) routine use of steroids for vasoplegia; (3) superurgent complete revascularisation timing after CULPRIT-SHOCK; (4) microcirculatory monitoring; (5) outcome prediction with machine-learning models; (6) the ethical allocation of MCS and transplant.[1]

The mantra, and the viva honesty line

[1]

The mantra: watch the perfusion not the pressure, stage with SCAI, revascularise early, defend the MAP, and escalate to a pump before the spiral is irreversible.[6][13]

Ward-round test — three stems, thirty seconds each

Stem 1 — the post-PCI patient from the top of the topic (answer)

A 64-year-old man, six hours after primary PCI for an anterior STEMI, becomes confused with oliguria; BP 88/60, HR 118, cool mottled peripheries, bibasal crackles, lactate 5.2 mmol/L. What is the diagnosis, the stage, and the immediate management? Model: Cardiogenic shock complicating acute MI — SCAI stage C (classic): hypoperfusion with hypotension, raised wedge (the crackles), raised lactate. Perfusion is failing while the cuff is still being debated. Immediate management: ABCDE and oxygen, arterial line and central access, a bedside echo to exclude a mechanical complication, an inotrope (dobutamine 2 to 20 mcg/kg/min) plus noradrenaline to MAP at least 65, careful diuresis for the congestion, and re-discussion of revascularisation (the stent is open, so support the circulation and watch for recovery; if deteriorating, escalate to MCS). Do not flood him with fluid — the wedge is already high.[1][13]

Stem 2 — the clear-lung-fields shock (answer)

A 70-year-old with an inferior STEMI has BP 84/58, a raised JVP with a Kussmaul sign, and clear lung fields; he has just been given sublingual GTN by the nurse and has dropped his pressure further. What is this, and what is the single most important change in management? Model: Right ventricular infarction — the clear-lung-fields shock. The RV is preload-dependent and the GTN has just collapsed it. Stop the nitrates, avoid diuretics and beta-blockers, and give a fluid challenge (250 mL balanced crystalloid boluses) to restore RV preload, targeting a raised JVP without pulmonary oedema. Reperfuse the RCA (PCI); add dobutamine if hypotension persists despite adequate preload. Maintain AV synchrony (atrial infarct and AV block are common). Record V4R to confirm RV involvement.[9]

Stem 3 — the day-4 new murmur (answer)

A 58-year-old woman, four days after an inferior STEMI that was managed medically, suddenly develops pulmonary oedema and shock with a harsh pansystolic murmur and a thrill at the lower left sternal edge. What is the diagnosis, the investigation, and the disposition? Model: Ventricular septal rupture (day 3 to 6 post-MI) — a loud pansystolic murmur with a thrill at the lower left sternal edge plus biventricular failure is VSR until proven otherwise (distinguish from papillary muscle rupture, which is apical, radiates to the axilla, and usually has no thrill). Emergency bedside echo with colour Doppler confirms the left-to-right shunt. Disposition: emergency surgical closure (or a percutaneous device in selected cases), with MCS (IABP or Impella) as a bridge and a vasodilator (nitroprusside) to reduce afterload if BP tolerates. This is a surgical emergency — mortality without surgery is catastrophic.[9]

References

1. [1]Hochman JS, Sleeper LA, Webb JG, et al. Early revascularization in acute myocardial infarction complicated by cardiogenic shock. SHOCK Investigators. Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock N Engl J Med, 1999.PMID 10460813
2. [2]Hochman JS, Sleeper LA, White HD, et al. One-year survival following early revascularization for cardiogenic shock JAMA, 2001.PMID 11176812
3. [3]Thiele H, Zeymer U, Neumann FJ, et al. Intraaortic balloon support for myocardial infarction with cardiogenic shock N Engl J Med, 2012.PMID 22920912
4. [4]Thiele H, Akin I, Sandri M, et al. PCI Strategies in Patients with Acute Myocardial Infarction and Cardiogenic Shock N Engl J Med, 2017.PMID 29083953
5. [5]Alexander JH, Reynolds HR, Stebbins AL, et al. Effect of tilarginine acetate in patients with acute myocardial infarction and cardiogenic shock: the TRIUMPH randomized controlled trial JAMA, 2007.PMID 17387132
6. [6]Baran DA, Grines CL, Bailey S, et al. SCAI clinical expert consensus statement on the classification of cardiogenic shock: This document was endorsed by the American College of Cardiology (ACC), the American Heart Association (AHA), the Society of Critical Care Medicine (SCCM), and the Society of Thoracic Surgeons (STS) in April 2019 Catheter Cardiovasc Interv, 2019.PMID 31104355
7. [7]Naidu SS, Baran DA, Jentzer JC, et al. SCAI SHOCK Stage Classification Expert Consensus Update: A Review and Incorporation of Validation Studies: This statement was endorsed by the American College of Cardiology (ACC), American College of Emergency Physicians (ACEP), American Heart Association (AHA), European Society of Cardiology (ESC) Association for Acute Cardiovascular Care (ACVC), International Society for Heart and Lung Transplantation (ISHLT), Society of Critical Care Medicine (SCCM), and Society of Thoracic Surgeons (STS) in December 2021 J Am Coll Cardiol, 2022.PMID 35115207
8. [8]Jentzer JC, van Diepen S, Barsness GW, et al. Cardiogenic Shock Classification to Predict Mortality in the Cardiac Intensive Care Unit J Am Coll Cardiol, 2019.PMID 31548097
9. [9]Byrne RA, Rossello X, Coughlan JJ, et al. 2023 ESC Guidelines for the management of acute coronary syndromes Eur Heart J, 2023.PMID 37622654
10. [10]Forrester JS, Diamond G, Chatterjee K, et al. Medical therapy of acute myocardial infarction by application of hemodynamic subsets (first of two parts) N Engl J Med, 1976.PMID 790191
11. [11]Forrester JS, Diamond GA, Chatterjee K, et al. Medical therapy of acute myocardial infarction by application of hemodynamic subsets (second of two parts) N Engl J Med, 1976.PMID 790194
12. [12]Heidenreich PA, Bozkurt B, Aguilar D, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines J Am Coll Cardiol, 2022.PMID 35379503
13. [13]Tehrani BN, Truesdell AG, Psotka MA, et al. A Standardized and Comprehensive Approach to the Management of Cardiogenic Shock JACC Heart Fail, 2020.PMID 33121700