Flecainide is Contraindicated After STEMI
Flecainide is absolutely contraindicated in patients who have experienced a ST-Elevation Myocardial Infarction (STEMI) due to increased risk of mortality and should not be used in this population. 1
Evidence Against Flecainide Use Post-STEMI
The FDA drug label for flecainide explicitly states that it "should not be used in patients with recent myocardial infarction" 1. This contraindication is based on robust evidence from the landmark Cardiac Arrhythmia Suppression Trial (CAST), which demonstrated:
- A 2.5-fold increase in total mortality (7.7% vs 3.0%) in post-MI patients treated with flecainide compared to placebo 2
- A 3.6-fold increase in deaths from arrhythmia and nonfatal cardiac arrests (4.5% vs 1.2%) 2
The CAST study was so definitive that it was terminated early due to these significant safety concerns, establishing one of the clearest contraindications in cardiovascular pharmacology.
Mechanism of Harm
Flecainide's proarrhythmic effects are particularly dangerous in post-STEMI patients due to:
- Its sodium channel blocking properties that slow conduction in cardiac tissue
- Increased risk of ventricular arrhythmias in the setting of myocardial scarring
- Potential for exacerbating electrical instability in recently damaged myocardium
Alternative Antiarrhythmic Options Post-STEMI
For patients requiring antiarrhythmic therapy after STEMI, guidelines recommend:
For ventricular arrhythmias: Implantable cardioverter-defibrillator (ICD) therapy for patients who develop sustained ventricular tachycardia/ventricular fibrillation more than 48 hours after STEMI (provided the arrhythmia is not due to transient ischemia, reinfarction, or metabolic abnormalities) 3
For atrial fibrillation: Anticoagulation with vitamin K antagonists for patients with STEMI and atrial fibrillation with CHADS2 score ≥2 3
For rate control: Beta-blockers are the preferred agents for rate control in post-STEMI patients with supraventricular arrhythmias 3
For rhythm control when necessary: Amiodarone is the preferred antiarrhythmic for rhythm control in patients with structural heart disease, including post-MI 3
Special Considerations
While some recent research suggests flecainide might be safe in stable coronary artery disease without prior MI 4, this does not apply to post-STEMI patients. The distinction is critical:
- Stable CAD without prior infarction may have intact myocardium
- Post-STEMI patients have definitive myocardial damage and scarring
Conclusion
The evidence against using flecainide after STEMI is overwhelming and consistent across guidelines. The increased mortality risk demonstrated in the CAST trial established a clear contraindication that remains valid today. Alternative antiarrhythmic strategies should be employed for post-STEMI patients requiring arrhythmia management.