Wide QRS tachycardia after myocardial infarction — VT case discussion

Objectives

1. Treat a haemodynamically not-tolerated wide QRS tachycardia as VT and terminate it. ^{[1] [2]}
2. Investigate reversible causes and the substrate. ^[1]
3. Make the ICD decision with its ESC class and the trial evidence. ^[1]
4. Plan for recurrence. ^[1]

Candidate brief

You are the cardiology registrar called to the emergency department. In twenty minutes, take the case from the first minute through the ICD decision and follow-up, quoting guideline classes and trial evidence. ^[1]

Expected actions

• Recognise that this tachycardia is not haemodynamically tolerated, and treat the wide QRS tachycardia as VT: the default diagnosis should be VT until proven otherwise.^[2]
• Perform immediate synchronised DC cardioversion, the ESC first-line treatment for haemodynamically not-tolerated SMVT (Class I, level B); use an unsynchronised shock if synchronisation is not possible.^[1]
• Avoid intravenous verapamil, which is not recommended in broad QRS tachycardia of unknown mechanism (Class III, level B).^[1]
• After termination, investigate reversible causes such as electrolyte imbalance, ischaemia, hypoxaemia and fever (Class I, level C; the list is not exhaustive), and correct the hypokalaemia, because hypokalaemia may trigger VA.^[1]
• For newly documented VA, a baseline 12-lead ECG, recording of the VA on 12-lead ECG whenever possible, and an echocardiogram are recommended as first-line evaluation (Class I, level C).^[1]
• In the absence of a reversible cause, recommend an ICD for haemodynamically not-tolerated VT (Class I, level A); in CAD, the Table 24 row applies to VF or not-tolerated VT occurring later than 48 h after MI without ongoing ischaemia (Class I, level A).^[1]
• Check the general ICD conditions: an expectation of good-quality survival of more than 1 year (Class I, level C), and evaluate whether she could benefit from CRT-defibrillator (Class I, level C).^[1]
• Ensure optimal medical treatment for her heart failure with reduced EF: ACE-I/ARB/ARNI, MRA, beta-blocker and SGLT2 inhibitor are indicated in all heart failure patients with reduced EF (Class I, level A).^[1]
• Quote the evidence: in AVID, unadjusted overall survival at 3 years was 75.4% with an ICD versus 64.1% with antiarrhythmic drugs.^[5] The secondary prevention meta-analysis showed an ICD-versus-amiodarone all-cause death HR of 0.72, and patients with LVEF of 35% or less derived significantly more benefit.^[6]
• Plan for recurrence: in CAD, if recurrent, symptomatic SMVT or ICD shocks for SMVT occur on a beta-blocker, adding oral amiodarone or replacing the beta-blocker with sotalol should be considered (Class IIa, level B). In CAD, if recurrent, symptomatic SMVT or ICD shocks for SMVT occur despite chronic amiodarone, catheter ablation is recommended in preference to escalating AADs (Class I, level B).^[1]

Marking

Pass:

• cardioverts immediately as first-line treatment.
• treats the wide QRS tachycardia as VT.
• corrects potassium and searches for reversible causes.
• states the Class I, level A secondary prevention ICD indication.
• names ablation as the recommended step in CAD for recurrent, symptomatic SMVT or ICD shocks for SMVT despite chronic amiodarone.

Fail:

• gives intravenous verapamil, or delays cardioversion for adenosine, in a hypotensive patient.
• treats hypokalaemia as the whole explanation and omits the ICD discussion, although ESC says that, despite a possible correctable cause, the need for ICD implantation should be considered based on an individual evaluation of the risk of subsequent VA/SCD.
• quotes an ICD class without its population.