Randomised trial of outcome after myocardial infarction in patients with frequent or repetitive ventricular premature depolarisations: CAMIAT. Canadian Amiodarone Myocardial Infarction Arrhythmia Trial Investigators.

BACKGROUND: Survivors of acute myocardial infarction with frequent or repetitive ventricular premature depolarisations (VPDs) have higher mortality 1-2 years after the event than those without VPDs. Although there is no therapy of proven efficacy for such patients, previous studies of amiodarone have been encouraging. CAMIAT was a randomised double-blind placebo-controlled trial designed to assess the effect of amiodarone on the risk of resuscitated ventricular fibrillation or arrhythmic death among survivors of myocardial infarction with frequent or repetitive VPDs (> or = 10 VPDs per h or > or = 1 run of ventricular tachycardia).

METHODS: Patients from 36 Canadian hospitals were randomly assigned amiodarone or placebo; a loading dose of 10 mg/kg daily for 2 weeks, a maintenance dose of 300-400 mg daily for 3.5 months, 200-300 mg daily for 4 months, and 200 mg for 5-7 days per week for 16 months. Patients were followed up for 2 years. The primary outcome was the composite of resuscitated ventricular fibrillation or arrhythmic death.

FINDINGS: We recruited 1202 patients (606 in the amiodarone group and 596 in the placebo group). The mean follow-up was 1.79 years (SD 0.44). In the efficacy analysis, resuscitated ventricular fibrillation or arrhythmic death occurred in 39 (6.9%) [corrected] patients in the placebo group and in 25 (4.5%) [corrected] in the amiodarone group (relative-risk reduction 48.5% [95% CI 4.5 to 72.2], p = 0.016). In the intention-to-treat analysis, primary outcome events occurred in 24 (6.9%) patients in the placebo group and in 15 (4.5%) in the amiodarone group (38.2% [95% CI -2.1 to 62.6], p = 0.029). The absolute-risk reductions were greatest among patients with congestive heart failure or a history of myocardial infarction.

INTERPRETATION: Amiodarone reduces the incidence of ventricular fibrillation or arrhythmic death among survivors of acute myocardial infarction with frequent or repetitive VPDs. Treatment decisions for individual survivors should require an assessment of their baseline risk factors and judgments based on the synthesis of our findings with those of related trials.