NSTE-ACS — structured viva

Stem

Practice viva. You are the cardiology registrar on call. The examiner hands you a referral: "NSTEMI, troponin positive, pain-free, please advise." The viva follows the patient from the ECG to follow-up after discharge; Branch F considers an alternative angiographic finding.

Branch A — Definitions

Examiner: What separates unstable angina from NSTEMI, and why is ACS not the same as MI?

Strong answer: ESC 2023 defines UA as myocardial ischaemia at rest or on minimal exertion without acute cardiomyocyte injury or necrosis; troponin stays below the 99th centile.^[1] In ESC 2023, NSTEMI shows a typical troponin rise and fall meeting the fourth universal definition of MI (2018), a framing now dated.^[1] The current Fifth UDMI (2026) requires acute myocardial injury, a rise and/or fall with at least one value above the sex-specific 99th percentile URL.^[29] It adds at least one feature: symptoms or other evidence of acute ischaemia, including new ischaemic ECG changes or pathological Q waves, or imaging evidence.^[29] Imaging evidence means an acute coronary pathology, or new loss of viable myocardium or a new regional wall motion abnormality in an ischaemic pattern.^[29] UA has become less common with high-sensitivity assays.^[1] ESC 2023 stresses that ACS and MI are closely related but not the same.^[1] In ESC 2023, AMI is necrosis in the setting of acute ischaemia, including the dated Fourth UDMI types 1 and 2–5, whereas myocardial injury is troponin release from non-ischaemic mechanisms that does not meet MI criteria.^[1] The Fifth UDMI (2026) classifies MI as primary, secondary or procedure-related, and acute myocardial injury can be ischaemic or non-ischaemic.^[29]

Follow-up: How do you separate what ESC 2023 calls type 2 MI, and how does the Fifth UDMI reclassify it? Answer: ESC 2023 defines type 2 MI as ischaemic injury from supply–demand mismatch without acute atherothrombosis, for example from coronary embolus, dissection or spasm, or from hypoxia, hypotension, anaemia, tachycardia or bradycardia.^[1] The current Fifth UDMI (2026) classes supply–demand MI from another acute condition as secondary MI, considered when acute myocardial injury comes with ischaemic symptoms or ECG changes.^[29] Where imaging is feasible and appropriate, it is confirmed by obstructive coronary artery disease (≥70% stenosis, or ≥50% if flow-limiting) without acute coronary pathology, or a new ischaemic-pattern wall motion abnormality or lost viability.^[29] Coronary dissection, embolism and vasospasm, grouped with type 2 MI under the Fourth UDMI, are primary MI under the Fifth UDMI (2026).^[29] For type 2 MI, ESC 2023 advises an algorithmic approach, and management focuses on the precipitant, with strict control of cardiovascular risk factors, because no specific drug therapy is recommended.^[1]

Branch B — Troponin

Examiner: Walk me through the ESC 0 h/1 h algorithm.

Strong answer: ESC 2023 recommends an algorithmic approach with serial hs-cTn (Class I, Level B): 0 h/1 h is the best option and 0 h/2 h the second-best, for ED patients with suspected NSTEMI and no indication for immediate angiography.^[1] A very low 0 h value (only if chest pain began over 3 h before the 0 h sample), or a low value with no 1 h change, rules out. A high 0 h value or a 1 h change rules in; the rest are observed.^[1] Rule-out NPV has exceeded 99% and rule-in PPV has been about 70–75%.^[1] The observe group has a mortality comparable to rule-in and gets a third troponin at 3 h (± echocardiography).^[1] Cut-offs are assay specific.^[1]

Follow-up: What is different in the US guideline? Answer: ACC/AHA 2025 uses clinical decision pathways with hs-cTn at 0 h and 1 to 2 hours, notes that men and women may have different cut-offs, and requires at least 3 hours from symptom onset for a single-value pathway.^[2] ESC 2023 instead keeps uniform cut-offs as the standard of care until automated tools incorporating age, eGFR, time from chest pain onset and sex are available.^[1]

Branch C — Risk and timing

Examiner: When does this patient go to the catheterisation laboratory?

Strong answer: Under ESC 2023, any very high-risk feature means an immediate invasive strategy is recommended (Class I, Level C). The features are haemodynamic instability or cardiogenic shock, recurrent or refractory chest pain despite medical treatment, in-hospital life-threatening arrhythmias, mechanical complications of MI, acute heart failure presumed secondary to ongoing myocardial ischaemia, or recurrent dynamic ST-segment or T-wave changes, particularly intermittent ST-segment elevation.^[1] Any high-risk feature (confirmed NSTEMI by the ESC hs-cTn algorithm, dynamic ST-T changes, transient ST elevation, GRACE over 140) means early angiography within 24 h should be considered (Class IIa, Level A), with an inpatient invasive strategy recommended (Class I, Level A).^[1] ACC/AHA 2025 recommends an immediate invasive strategy under 2 hours from admission for unstable patients and an invasive approach during hospitalisation at intermediate or high risk, both with intent to revascularise.^[2]

Follow-up: Does early angiography save lives? Answer: ESC 2023 says meta-analyses show no superiority of early over routine invasive strategies for death or non-fatal MI, although early strategies were associated with less recurrent or refractory ischaemia and a shorter hospital stay.^[1] In TIMACS, the 6-month composite of death, MI or stroke was 9.6% with early vs 11.3% with delayed intervention (HR 0.85, P=0.15), but early intervention improved it in the highest-risk third (HR 0.65).^[7] ICTUS could not show superiority of an early invasive over a selectively invasive strategy in troponin-positive patients given optimised medical therapy.^[6][26]

Branch D — Antiplatelets

Examiner: Do you load a P2Y12 inhibitor now?

Strong answer: Not routinely if angiography is planned within 24 h: ESC 2023 does not recommend routine pretreatment before the anatomy is known in that setting (Class III, Level A).^[1] If an early invasive strategy (under 24 h) is not expected, ESC 2023 says pretreatment may be considered in patients without HBR (Class IIb, Level C); ACC/AHA 2025: when angiography is scheduled more than 24 h away, upstream clopidogrel or ticagrelor may be considered.^[1][2] In ACCOAST, prasugrel pretreatment vs placebo did not significantly change the 7-day ischaemic composite (HR 1.02) and increased TIMI major bleeding through day 7 (HR 1.90).^[13]

Follow-up: And at PCI? Answer: ESC 2023 says prasugrel should be considered in preference to ticagrelor for patients proceeding to PCI (Class IIa, Level B), based on ISAR-REACT 5 (1-year composite of death, MI or stroke 6.9% with prasugrel vs 9.3% with ticagrelor).^[1][12] ESC 2023: prior stroke is a contraindication for prasugrel, and ticagrelor (180 mg oral loading, then 90 mg twice daily) is the potent alternative. ACC/AHA 2025 adds that aspirin should always be 100 mg daily or less with ticagrelor.^[1][2]

Branch E — Anticoagulation

Examiner: Which anticoagulant, and what if angiography is three days away?

Strong answer: For immediate or early angiography, ESC 2023 recommends UFH, with enoxaparin to be considered as an alternative (Class IIa, Level B).^[1] If early angiography is not anticipated, fondaparinux 2.5 mg SC daily (avoid if CrCl is under 20 mL/min) is recommended (Class I, Level B), in preference to enoxaparin, with a full-dose UFH bolus at PCI because of guiding-catheter thrombus.^[1] OASIS-5 found fondaparinux noninferior to enoxaparin for the 9-day composite of death, MI or refractory ischaemia, with major bleeding at 9 days of 2.2% with fondaparinux vs 4.1% with enoxaparin.^[17]

Follow-up: Any traps? Answer: In general, crossover between anticoagulants, especially UFH and LMWH, should be avoided (ESC 2023), except for adding UFH to fondaparinux at PCI. Discontinuation of parenteral anticoagulation should be considered immediately after an invasive procedure (Class IIa, Level C), with exceptions such as a confirmed LV aneurysm with thrombus or AF requiring anticoagulation.^[1]

Branch F — Non-obstructive coronaries (MINOCA)

Examiner: Suppose instead that angiography shows no stenosis of 50% or more. Now what?

Strong answer: That is a working diagnosis of MINOCA under ESC 2023, which needs a diagnostic algorithm to find the cause (Class I, Level C).^[1] The current Fifth UDMI (2026) renames MINOCA myocardial injury with non-obstructive coronary arteries, a working diagnosis; if MI is confirmed, it is classified as primary, secondary or procedure-related.^[29] If angiography alone does not establish the cause, ventriculography with LV end-diastolic pressure, microvascular or vasoreactivity testing and intravascular imaging can be useful (ESC 2023).^[1] CMR is recommended after invasive angiography if the final diagnosis is not clear (Class I, Level B); it can identify the cause in up to 87% and should be performed as soon as possible, ideally during the index admission.^[1]

Branch G — After discharge

Examiner: Back to the main scenario: he had PCI to his culprit lesion. He has minor bleeding on prasugrel at 2 weeks. Can you de-escalate?

Strong answer: ESC 2023 does not recommend de-escalation in the first 30 days (Class III, Level B); beyond 30 days it may be considered to reduce bleeding (Class IIb, Level A for de-escalation as an alternative strategy).^[1] TROPICAL-ACS stepped down from prasugrel (1 week prasugrel, 1 week clopidogrel, then platelet-function-guided maintenance from day 14 after discharge) and was non-inferior to 12 months of prasugrel for the 1-year net clinical benefit composite (cardiovascular death, MI, stroke or BARC 2 or higher bleeding). ESC 2023 still cites a potential rise in ischaemic events with de-escalation in the first 30 days.^[21][1] If he met HBR criteria, ESC 2023 says aspirin or P2Y12 inhibitor monotherapy after 1 month of DAPT may be considered (Class IIb, Level B).^[1]

Follow-up: And if he had AF? Answer: The ESC 2023 default applies in AF with a CHA2DS2-VASc score of 1 or more in men or 2 or more in women. It is up to 1 week of triple therapy, then a NOAC at the stroke-prevention dose plus a single oral antiplatelet, preferably clopidogrel, for up to 12 months (Class I, Level A). Prasugrel or ticagrelor in triple therapy is not recommended (Class III, Level C).^[1] ACC/AHA 2025 recommends, in patients who require long-term anticoagulation, stopping aspirin 1 to 4 weeks after PCI and continuing a P2Y12 inhibitor, preferably clopidogrel.^[2]