A large randomized trial in survivors of myocardial infarction with frequent premature ventricular complexes showed that suppression of ectopy with encainide or flecainide INCREASED total mortality compared with placebo. What is the most likely explanation?

• A Hypokalemia caused by renal tubular effects of the drugs
• B Excess bradycardia and atrioventricular block
• C Accelerated atherosclerosis from lipid effects
• D Proarrhythmic sudden death from sodium channel blockade in scarred myocardium ✓

Explanation

This describes the CAST trial, which demonstrated that class IC agents suppress ventricular ectopy after myocardial infarction yet increase mortality through proarrhythmia, specifically reentrant ventricular tachycardia in ischemic scar where slowed conduction favors reentry. This finding established that ectopy suppression is not a surrogate for survival benefit and that class IC agents must be avoided in structural heart disease. Bradycardia, lipid effects and potassium changes were not implicated.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.