Effects of glibenclamide on ventricular fibrillation in non-insulin-dependent diabetics with acute myocardial infarction.

BACKGROUND: Glibenclamide, a hypoglycemic sulfonylurea, has shown antiarrhythmic effects in acutely ischemic myocardium. The aim of the present study was to evaluate the effectiveness of the drug in preventing ventricular fibrillation in diabetic patients with acute myocardial infarction.
METHODS: We studied 232 patients with non-insulin-dependent diabetes mellitus (106 on glibenclamide, group A1; 126 treated with another hypoglycemic drug or with diet only, group A2) and 830 non-diabetic people. All the patients were admitted to our coronary care unit with their first myocardial infarction.
RESULTS: Ventricular fibrillation occurred in 1.9% of group A1, 7.9% of group A2, and 9.9% of the non-diabetic (A1 versus A2, P < 0.05; A2 versus the non-diabetic group, NS; A1 versus the non-diabetic group, P < 0.01). Sustained ventricular tachycardia was not significantly different among the groups.
CONCLUSIONS: The antiarrhythmic effectiveness of glibenclamide might be related to its blocking action on the ATP-dependent potassium channel, with consequent attenuation of the efflux of potassium induced by ischemia. We also observed a higher mortality rate resulting from heart failure in group A2 than in group A1 or the non-diabetic group. Since glibenclamide has never shown significant effects on myocardial contractility, this finding remains to be elucidated. Glibenclamide therefore appears to have an antifibrillatory effect in acute myocardial infarction; with respect to acute coronary events, the drug might be able to prevent ventricular fibrillation, which is most often fatal when it occurs before hospitalization.