Risk prediction in post-infarction patients with moderately reduced left ventricular ejection fraction by combined assessment of the sympathetic and vagal cardiac autonomic nervous system

Aim: Most deaths after myocardial infarction (MI) occur in patients with normal or moderately reduced left ventricular ejection fraction (LVEF > 35%). Periodic repolarization dynamics (PRD) and deceleration capacity (DC) are novel ECG-based markers related to sympathetic and vagal cardiac autonomic nervous system activity. Here, we test the combination of PRD and DC to predict risk in post-infarction patients with LVEF > 35%. Methods and results: We included 823 survivors of acute MI with LVEF > 35%, aged <= 80 years and in sinus rhythm. PRD and DC were obtained from 30-min ECG-recordings within the second week after index infarction and dichotomized at established cut-off values of >= 5.75 deg(2) and <= 2.5ms, respectively. Patients were classified as having normal (CAF 0), partly abnormal (DC or PRD abnormal; CAF 1) or abnormal cardiac autonomic function (DC and PRD abnormal; CAF 2). Primary endpoint was 5-year all-causemortality. Within the first 5 years of follow-up, 51 patients died (6.2%). PRD and DC effectively stratified patients into low-risk (CAF 0; n = 562), intermediate-risk (CAF 1; n = 193) and high-risk patients (CAF 2; n = 68) with cumulative 5-year mortality rates of 2.9%, 9.4% and 25.2%, respectively (p < 0.001). On multivariable analyses, CAF was independent from established risk factors (GRACE-score, diabetes mellitus, mean heart rate, heart rate variability). Addition of CAF significantly improved the model (increase of C-statistics from 0.732 (0.651-0.812) to 0.777 (0.703-0.850), p = 0.047; continuous NRI (0.400, 95% CI 0.230-0.560, p < 0.001); IDI (0.056, 95% CI 0.022-0.122, p < 0.001)). Conclusion: CAF identifies new high-risk post-MI patients with LVEF >35% which might benefit from prophylactic strategies. (C) 2017 Elsevier B.V. All rights reserved.