Reduced Beat-to-Beat Changes of Heart Rate: An Important Risk Factor after Acute Myocardial Infarction

Abstract

The prognostic significance of heart rate variability derived from 24-hour electrocardiographic recordings was investigated in 250 patients with acute myocardial infarction. During a follow-up of 6 months 15 patients experienced a serious arrhythmic event. These patients showed a significantly reduced beat to beat variability (p = 0.006), a slightly reduced 5-min variability (p = 0.04) and no significant differences in the 24-hour variability compared to the patients free of arrhythmic events. Based on Cox proportional hazard analysis, beat to beat variability remained an independent risk factor (p = 0.0036) in addition to the presence or absence of ventricular late potentials (p = 0.0004) and history of previous infarction (p = 0.04).