Lidocaine prophylaxis for fatal ventricular arrhythmias after acute myocardial infarction.

OBJECTIVE

To compare the efficacy and safety of a 40-hour lidocaine infusion after completion of a 8-hour open-label infusion for prophylaxis of primary ventricular fibrillation in patients with uncomplicated acute myocardial infarction.

METHODS

This was a double-blind, randomized placebo-controlled trial held in the coronary care unit of a large nonprofit hospital. We studied 200 patients with uncomplicated acute myocardial infarction in Killip class I or II who came to the hospital within 6 hours of onset of symptoms and 22 patients who had ventricular fibrillation before the start of the study. Intervention consisted of an 8-hour lidocaine infusion followed by placebo or lidocaine for an additional 40 hours. The infusion rate was adjusted in patients > or = 70 years old and in those < 50 kg or > or = 90 kg. Measurements recorded were baseline demographic characteristics, incidence of ventricular arrhythmias, adverse reactions, and death.

RESULTS

New congestive heart failure developed during the randomized phase in 9% of patients receiving lidocaine and in 2% of patients receiving placebo (p = 0.03). Ventricular fibrillation did not occur during the treatment period, and sustained ventricular tachycardia developed in one patient receiving placebo. The in-hospital mortality rate was comparable in both groups (4% versus 2%; p = 0.68) but was much higher (13.6%) in patients with initial ventricular fibrillation not included in the randomized study.

CONCLUSIONS

A 40-hour age- and weight-adjusted lidocaine infusion administered after an initial 8-hour infusion provoked more congestive heart failure than placebo. In view of the absence of ventricular fibrillation episodes with both infusions, caution should be used when lidocaine is administered for longer than 8 hours in patients with uncomplicated myocardial infarction.