HEART-RATE-VARIABILITY AS A MEANS OF ASSESSING PROGNOSIS AFTER ACUTE MYOCARDIAL-INFARCTION - A 3-YEAR FOLLOW-UP-STUDY

Aims The present study evaluated the prognostic value of heart rate va riability after acute myocardial infarction in comparison with other k nown risk factors. The cut-off points that maximized the hazards ratio were also explored. Patients and methods Heart rate variability was a ssessed with 24 h ambulatory electrocardiography in 74 patients with a cute myocardial infarction, 4 +/- 2 days after hospital admission and in 24 healthy controls. Patients were followed for 36 +/- 15 months. R esults During follow-up, 18 patients died, nine suffered a non-fatal i nfarction and 20 underwent revascularization procedures. Heart rate va riability was higher in survivors than in non-survivors (P=0.005). Thi s difference was found at higher statistical levels when comparing non -survivors vs controls (P=0.0002). A similar statistically significant difference was also found between survivors vs controls (P=0.04). Pat ients suffering non-fatal infarction and cardiac events (defined as de ath, non-fatal infarction or revascularization) had a lower heart rate variability than those without (P=0.03 and P=0.03, respectively). Wit h multivariate regression analysis, decreased heart rate variability i ndependently predicted mortality and death or non-fatal infarction. Th e presence of a left ventricular ejection fraction <40% and a history of systemic hypertension were, however, stronger predictors. The cut-o ff points that maximized the hazards ratio using the Cox model differe d from those reported by others. Conclusion Decreased heart rate varia bility independently predicted poor prognosis after myocardial infarct ion. However, the cut-off points that should be used in clinical pract ice are still a matter for further investigation.