The American journal of cardiology
-
Randomized Controlled Trial Clinical Trial
Effects of propranolol on recovery of heart rate variability following acute myocardial infarction and relation to outcome in the Beta-Blocker Heart Attack Trial.
This study evaluated the effects of propranolol on recovery of heart rate variability (HRV) after acute myocardial infarction and its relation to outcome in the Beta-blocker Heart Attack Trial (BHAT). Beta blockers improve mortality after acute myocardial infarction, but through an unknown mechanism. Depressed HRV, a measure of autonomic tone, predicts mortality after acute myocardial infarction. ⋯ Recovery of HF, the strongest HRV predictor of outcome, and propranolol therapy independently predicted outcome. In summary, after acute myocardial infarction, propranolol therapy improves recovery of parasympathetic tone, which correlates with improved outcome, and decreases morning sympathetic predominance. These findings may elucidate the mechanisms by which beta blockers decrease mortality and reduce the early morning risk of sudden death after acute myocardial infarction.