Heart rate turbulence and other autonomic risk markers for arrhythmia risk stratification in dilated cardiomyopathy

Abstract

Background Noninvasive arrhythmia risk stratification in patients with nonischemic dilated cardiomyopathy (DCM) using autonomic markers have yielded disappointing results. Heart rate turbulence is a new method to assess cardiac autonomic function. Aim The aim of the study was to compare the predictive value of heart rate turbulence with those of conventional autonomic risk markers for ventricular tachyarrhythmic events in patients with DCM. Methods The predictive value of heart rate turbulence, baroreflex sensitivity (phenylephrine method), and heart rate variability was assessed in patients with symptomatic congestive heart failure due to DCM who were in sinus rhythm and had a 24-hour Holter recording. Patients were followed for a combined end point of ventricular tachyarrhythmic events. Results A total of 114 patients (mean left ventricular ejection fraction, 28 ± 11%), included in the Frankfurt DCM database between 1996 and 2000, fulfilled the criteria for inclusion in this study. Determinate test results were obtained for heart rate variability in 98%, for baroreflex sensitivity in 90%, and for heart rate turbulence in 75% of patients ( P = .008). Correlation between the different autonomic markers were only modest ( r values, 0.36-0.43). During a follow-up of 22 ± 17 months, an end point event occurred in 15 patients. On univariate analysis, left ventricular ejection fraction and baroreflex sensitivity were significant predictors of arrhythmic events. On multivariate analysis, only baroreflex sensitivity remained an independent predictor ( χ 2 = 3.17; P = .07). Conclusion Reliable analysis of heart rate turbulence is possible in approximately 75% of eligible patients with DCM. Whereas blunted baroreflex sensitivity is a predictor of arrhythmic events, heart rate variability and turbulence do not yield predictive power in these patients.