Prognostic value of decreased heart rate variability in long-term follow-up in patients with acute myocardial infarction treated with thrombolysis

Introduction: In previous decades, the analysis of heart rate variability (HRV) provided a non-invasive method of assessing autonomic influence for cardiovascular risk stratification. The aim of this study was to determine whether HRV analysis can still perform a similar function in the present day.
Material and methods: The study group consisted of 113 patients with acute myocardial infarction (AMI) treated with thrombolysis. In all patients echocardiography on the 10th day after myocardial infarction and 24-h Holter electrocardiographic recordings on the 12th day after myocardial infarction were performed. Five time domain measures were calculated from the time series of normal N-N intervals: SDNN, SDANN index, SDNN index, rMSSD and pNN50. The end points in follow-up were: death, non-fatal myocardial infarction (AMI) and unstable angina pectoris requiring hospitalization (API). The study group was divided into two subgroups on the basis of SDNN value and both groups were analysed.
Results: At follow-up (mean 65 months, range 36 to 96 months) we observed clinical events in 44 patients, including 17 deaths, 8 cases of AMI and 20 cases of API requiring hospitalization. In the multivariate analysis SDNN Ł 70 ms as well as left ventricle ejection fraction < 30% were independent predictors of death.
Conclusions: SDNN Ł 70 ms remains a significant predictor of death in patients with MI treated with thrombolysis.