Wide-Complex Tachycardia in a Patient with Prior MI
A 62-year-old man with a prior anterior myocardial infarction 3 years ago and an ejection fraction of 30% calls emergency services for palpitations and near-syncope. On arrival he is alert but pale. Vitals: BP 92/60 mmHg, HR 168/min, respiratory rate 24/min, SpO2 94% on room air. ECG shows a regular wide-complex tachycardia with a QRS duration of 150 ms, a right bundle-branch morphology, and extreme axis deviation; there are no clear P waves and no capture/fusion beats. He has an IV in place. He reports no chest pain. He took his usual metoprolol this morning.
1. How do you classify this rhythm and what is your immediate management?
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A regular wide-complex tachycardia in a patient with prior MI and reduced EF is ventricular tachycardia until proven otherwise. Features supporting VT include: prior structural heart disease, QRS >140 ms, extreme axis, absence of typical bundle-branch block morphology, and no P waves. The absence of capture/fusion beats does not exclude VT.
Immediate management:
- Treat as unstable because of hypotension (92/60) and near-syncope. Per ACLS, unstable wide-complex tachycardia warrants synchronized cardioversion.
- Ensure pads, sedation if time permits, and airway readiness. If cardioversion is not immediately available or the patient deteriorates to pulselessness, proceed to defibrillation/CPR per cardiac arrest algorithm.
- Avoid verapamil/diltiazem and other AV nodal blockers for undifferentiated wide-complex tachycardia, as they can cause hemodynamic collapse in VT.
- Obtain 12-lead ECG, electrolytes, magnesium, and troponin, and correct reversible causes.
2. If the patient stabilizes after cardioversion, what diagnostic and long-term steps are indicated?
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After stabilization:
- Confirm the rhythm with a 12-lead ECG and review the post-cardioversion tracing for ischemia or QT prolongation.
- Echocardiography to reassess EF and structural disease; consider ischemia evaluation given prior MI.
- Electrophysiology consultation: in a patient with prior MI, reduced EF, and sustained VT, an implantable cardioverter-defibrillator is generally indicated for secondary prevention, along with evaluation for catheter ablation and antiarrhythmic therapy.
- Optimize guideline-directed medical therapy for heart failure and coronary disease, and correct electrolytes.
- Educate the patient about recurrence and device therapy.
Escalate promptly if VT recurs, if the patient becomes unstable, or if reversible causes are identified that need urgent treatment.