DEPRESSED NEAR RATE VARIABILITY AS AN INDEPENDENT PREDICTOR OF DEATH IN CHRONIC CONGESTIVE-HEART-FAILURE SECONDARY TO ISCHEMIC OR IDIOPATHIC DILATED CARDIOMYOPATHY

After acute myocardial infarction, depressed heart rate variability (H RV) has been proven to be a powerful independent predictor of a poor o utcome. Although patients with chronic congestive heart failure (CHF) have also markedly impaired HRV, the prognostic value of HRV analysis in these patients remains unknown. The aim of this study was to invest igate whether HRV parameters could predict survival in 102 consecutive patients with moderate to severe CHF (90 men, mean age 58 years, New York Heart Association [NYHA] class II to IV , CHF due to idiopathic d ilated cardiomyopathy in 24 patients and ischemic heart disease in 78 patients, ejection fraction [EF], 26%; peak oxygen consumption, 16.9 m l/kg/min) after exclusion of patients in atrial fibrilation with diabe tes or with chronic renal failure. In the prognostic analysis (Cox pro portional-hazards model, Kaplan-Meier survival analysis), the followin g factors were investigated: age, CHF etiology, NYHA class, EF, peak o xygen consumption, presence of ventricular tachycardia on Holter monit oring, and HRV measures derived from 24-hour electrocardiography monit oring, calculated in time (standard deviation of all normal RR interva ls [SDNN], standard deviation of 5-minute RR intervals [SDANN], mean o f all 5-minute-standard deviations of RR intervals [SD], root-mean-squ are of difference of successive RR intervals [rMSSD], and percentage o f adjacent RR intervals > 50 ms different [pNN50]) and frequency domai n (total) power [TP], power within low-frequency band [LF], and power within high-frequency band [HF]). During follow-up of 584 +/- 405 days (365 days in all who survived), 19 patients (19%) died (mean time to death: 307 +/- 315 days, range 3 to 989). Cox's univariate analysis id entified the following factors to be predictors of death: NYHA (p = 0. 003), peak oxygen consumption (p = 0.01), EF (p = 0.02), ventricular t achycardia on Holter monitoring (p = 0.02), ventricular tachycardia on Holter monitoring (p = 0.05), and among HRV measures: SDNN (p = 0.004 ), SDANN (p = 0.003), SD (p = 0.02), and LF (p = 0.003). In multivaria te analysis, HRV parameters (SDNN, SDANN, LF) were found to predict su rvival independently of NYHA functional class, EF, peak oxygen consump tion, and ventricular tachycardia on Holter monitoring. The Kaplan-Mei er survival curves revealed SDNN < 100 ms to be a useful risk factor; 1-year survival in patients with SDNN < 100 ms was 78% when compared w ith 95% in those with SDNN > 100 ms (p = 0.008). The coexistence of SD NN < 100 ms and a peak oxygen consumption < 14 ml/kg/min allowed ident ification of a group of 18 patients with a particularly poor prognosis (1-year survival 63% vs 94% in the remaining patients, p < 0.001). We conclude that depressed HRV on 24-hour ambulatory electrocardiography monitoring is an independent risk factor for a poor prognosis in pati ents with CHF. Whether analysis of HRV could be recommended in the ris k stratification for better management of patients with CHF needs furt her investigation. (C) 1997 by Excerpta Medica, Inc.