A 58-year-old man with a history of myocardial infarction presents with recurrent ventricular ectopy. Regarding the use of antiarrhythmic drugs in post-MI patients, all of the following are true EXCEPT:

Explanation

## Post-MI Antiarrhythmic Strategy: Evidence-Based Approach ### The CAST Trial and Its Implications **Key Point:** The CAST (Cardiac Arrhythmia Suppression Trial) trial of 1989 was a landmark study that fundamentally changed antiarrhythmic prescribing in post-MI patients. It demonstrated that Class I antiarrhythmics (both IA and IC) suppress ventricular ectopy but **increase mortality** in post-MI patients, despite effective arrhythmia suppression. ### Antiarrhythmic Choice in Post-MI Patients | Agent Class | Post-MI Safety | Evidence | Clinical Use | |-------------|----------------|----------|---------------| | Class IA | **Contraindicated** | CAST trial: increased mortality | Avoid | | Class IC | **Contraindicated** | CAST trial: increased mortality | Avoid (flecainide, propafenone) | | Class II (Beta-blockers) | **Recommended** | Reduce mortality, reduce reinfarction | First-line | | Class III (Amiodarone) | **Safe** | EMIAT, CAMIAT trials: neutral/beneficial | Second-line if needed | | Class IV (Verapamil, Diltiazem) | **Caution** | May increase mortality in systolic dysfunction | Avoid in HF | **High-Yield:** Both Class IA and Class IC agents are contraindicated post-MI. The CAST trial did not distinguish between them—both increase mortality. Class IA agents are NOT safer than Class IC agents in this population. ### Why Each Statement Is Correct (Except the Answer) **Option 0 (Class IC agents contraindicated):** - CAST trial definitively showed flecainide and encainide increase mortality post-MI - This is a **correct statement** **Option 1 (Amiodarone safe in post-MI):** - EMIAT (European Myocardial Infarction Amiodarone Trial) and CAMIAT trials showed amiodarone is safe - May reduce mortality in specific subgroups (e.g., ejection fraction <40%) - This is a **correct statement** **Option 2 (Beta-blockers first-line):** - Beta-blockers reduce mortality and reinfarction post-MI - Reduce sudden cardiac death from ventricular arrhythmias - This is a **correct statement** **Option 3 (Class IA preferred over Class IC):** ✗ - **Both Class IA and Class IC agents are contraindicated post-MI** - The CAST trial included Class IC agents (flecainide, encainide) and showed increased mortality - Class IA agents (quinidine, procainamide, disopyramide) also increase mortality post-MI - Neither is "preferred" over the other—both are avoided - This is an **incorrect statement** **Clinical Pearl:** The CAST trial was a watershed moment in cardiology. It taught us that suppressing arrhythmias does not always improve outcomes. In post-MI patients with ventricular ectopy, beta-blockers and amiodarone (if needed) are the agents of choice; Class I agents are avoided regardless of subclass. **Mnemonic:** **"CAST OUT Class I"** — The CAST trial cast out Class I antiarrhythmics from post-MI management.