Aim: To assess the relation between predischarge heart rate, heart rate variability, left ventricular ejection fraction, cardiac mortality, and recurrent non-fatal cardiac events in a 2-year follow-up of 95 patients after acute myocardial infarction or unstable angina.
Methods: Heart rate and heart rate variability were assessed in various portions of a complete 24-hour electrocardiographic recording obtained three weeks after hospital admission. Both the beginning and the length of the analyzed portions varied by 20 minutes (a total of 5,100 RR intervals).
Results: During a follow-up period of two or more years, there were 14 cardiac deaths in patients with previous myocardial infarction. Eight patients had recurrent cardiac event and were hospitalized. Twenty-nine patients had an effort-provoked angina. There was a significant positive association between the heart rate and cardiac mortality and significant inverse association between heart rate variability, left ventricula r ejection fraction, and cardiac mortality in postinfarction patients. There was no significant difference in heart rate, heart rate variability, and left ventricular ejection fraction between postinfarction patients and patients with unstable angina with or without secondary cardiac events.
Conclusion: Changes in the heart rate, heart rate variability, and left ventricular ejection fraction were associated with higher cardiac mortality in postinfarction patients. Secondary non-fatal cardiac events were not associated with these variables in patients after either myocardial infarction or unstable angina.