Most ventricular tachycardias occur due to a prior episode of which condition?

• A. Hypertrophic cardiomyopathy
• B. Myocardial infarction
• C. Atrial fibrillation
• D. Valvular disease

Answer: (B)

Ventricular tachycardia most often arises from reentry around scar tissue in the ventricle. When a myocardial infarction heals, fibrous scar forms and creates areas of slow conduction and block. This sets up a circuit that a rapidly propagating wavefront can repeatedly travel around, producing a sustained, regular VT. This scar-related substrate after MI is the most common setup for VT in adults.

While hypertrophic cardiomyopathy can cause VT through abnormal myocardial architecture, it’s less common as the trigger compared with post-infarction scar. Atrial fibrillation is a supraventricular tachycardia and doesn’t provide the myocardial substrate for VT. Valvular disease can be associated with arrhythmias, but it doesn’t explain the typical reentry substrate seen after myocardial infarction.