Heart rate recovery as a predictor of mortality with or without revascularization

Increased heart rate during graded exercise is related to increased sympathetic activity and withdrawal of vagal tone. Return of heart rate towards baseline immediately after exercise is usually due to resurgence of vagal tone. As it is an established fact that cardiovascular morbidity and mortality in part has direct relation with parasympathetic dysfunction, it is natural that reduced heart rate recovery (HRR) after exercise, a parameter of parasympathetic dysfunction, could be a predictor of morbidity and mortality. Accordingly 390 TMT positive patients were analysed for HRR as per standard guidelines and followed up for 5 years. While 244(62.6%) showed a normal HRR, 146(37.4%) showed an abnormal HRR. Abnormal HRR was more common in the elderly, in patients with higher resting heart rate, hypertension, diabetes mellitus, current smoking and prior established coronary artery disease (CAD). There were a total of 36 deaths (9.23%) during the 5 year follow-up period. There was mortality advantage in patients who were subjected to revascularization procedure in general (7.5% deaths in revascularised arm vs 10.4% in conservative arm). Analysis reveals persistence of such benefit in patients having normal HRR (2.85% deaths in revascularised arm vs 7.25% in conservative arm). However, mortality benefit was not observed among both groups of patients with abnormal HRR(16.6% deaths in revascularised vs 15.2% in conservatively managed7rpar;. Secondary end points like recurrent angina, arrhythmia, acute myocardial infarction, hospitalization for cardiovascular cause and heart failure were observed in significantly more number of cases with abnormal HRR in comparison to normal. We therefore conclude the abnormal HRR after TMT is an adverse prognostic indicator in patients with symptomatic CAD on long term follow-up.