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A critical appraisal of the cardiac arrhythmia suppression trial (CAST)
G V Naccarelli1, A H Dougherty, D Wolbrette
1The Electrophysiology Laboratory, Division of Cardiology, University of Texas Medical School at Houston.
Insights
The Cardiac Arrhythmia Suppression Trial (CAST) found that suppressing ventricular premature contractions (PVCs) with encainide or flecainide after myocardial infarction increased mortality. These antiarrhythmic drugs should be avoided in post-MI patients, except for beta-blockers.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Trials
Background:
- Ventricular ectopic activity post-myocardial infarction (MI), particularly with left ventricular dysfunction, is linked to sudden cardiac death.
- The hypothesis that suppressing these arrhythmias could reduce mortality was tested.
Purpose of the Study:
- To evaluate the efficacy of antiarrhythmic drug therapy in suppressing ventricular arrhythmias post-MI.
- To determine if suppressing ventricular premature contractions (PVCs) reduces sudden cardiac death in asymptomatic post-MI patients.
Main Methods:
- The Cardiac Arrhythmia Suppression Trial (CAST) enrolled asymptomatic patients post-MI with ventricular arrhythmias.
- Patients received encainide, flecainide, or placebo.
Main Results:
- Treatment with encainide or flecainide resulted in a 7.7% mortality rate at 10 months, compared to 3% in the placebo group.
- This indicates a significant increase in mortality and sudden cardiac death with these specific antiarrhythmic drugs.
Conclusions:
- PVC suppression using encainide or flecainide is not beneficial and potentially harmful in post-MI patients.
- Antiarrhythmic drug therapy, excluding beta-blockers, is questionable for asymptomatic ventricular arrhythmias post-MI.
- Flecainide and encainide should be avoided in this patient population.
Abstract:
The presence of ventricular ectopic activity in the post-myocardial infarction patient, especially associated with left ventricular dysfunction, has been associated with a high incidence of sudden cardiac death. To test the PVC hypothesis, that PVC suppression in asymptomatic patients with ventricular arrhythmias post-myocardial infarction might reduce sudden death rate, the cardiac arrhythmia suppression trial (CAST) was performed. In patients treated with encainide or flecainide, total mortality at 10 months was 7.7% compared to only 3% overall mortality on placebo. The increase in mortality and sudden cardiac death with these two drugs raised the question of whether PVC suppression in this group of patients should be attempted. In addition, the extrapolation of the results of this study to other patient groups has resulted in a change of our antiarrhythmic prescription habits. Criticism of the CAST study has included a low placebo mortality, which may have been secondary to entry of low-risk groups of patients, deaths in the open label titration groups not being included, and recent advances in thrombolysis and revascularization. In addition, this low placebo mortality may have been explained by the concept that drug-responsive arrhythmias may have more benign prognosis. The above results suggest that, except for the use of beta blockers, benefits of other anti-arrhythmic drug treatment in the post-infarction patient with asymptomatic benign and potentially lethal ventricular arrhythmias is questionable. Flecainide and encainide should be avoided in this group of patients.(ABSTRACT TRUNCATED AT 250 WORDS)