Reduction of QTc interval dispersion. Potential mechanism of cardiac protection of pyridostigmine bromide.

OBJECTIVE Parasympathetic dysfunction is an independent risk factor in individuals with coronary artery disease, and cholinergic stimulation is a potential therapeutical option. We determined the effects of pyridostigmine bromide, a reversible anticholinesterase agent, on electrocardiographic variables of healthy individuals. METHODS We carried out a cross-sectional, double blind, randomized, placebo-controlled study. We obtained electrocardiographic tracings in 12 simultaneous leads of 10 healthy young individuals at rest before and after oral administration of 45 mg of pyridostigmine or placebo. RESULTS Pyridostigmine increased RR intervals (before: 886+/-27 ms vs. after: 1054+/-37 ms) and decreased QTc dispersion (before: 72+/-9 ms vs. after: 45+/-3 ms), without changing other electrocardiographic variables (PR segment, QT interval, QTc, and QT dispersion). CONCLUSION Bradycardia and the reduction in QTc dispersion induced by pyridostigmine may effectively represent a protective mechanism if these results can be reproduced in individuals with cardiovascular diseases.