IngentaConnect Traditional and Nonlinear Heart Rate Variability Are Each Indepen...

Abstract:

Traditional and Nonlinear HRV and Mortality.

Introduction: Decreased heart rate variability (HRV) and abnormal nonlinear HRV shortly after myocardial infarction (MI) are risk factors for mortality. Traditional HRV predicts mortality in patients with a range of times post-MI, but the association of nonlinear HRV and outcome in this population is unknown.

Methods and Results: HRV was determined from 740 tapes recorded before antiarrhythmic therapy in Cardiac Arrhythmia Suppression Trial patients with ventricular premature contractions (VPCs) suppressed on the first randomized treatment. Patients were 70 ± 121 days post-MI. Follow up was 362 ± 241 days (70 deaths). The association between traditional time and frequency-domain HRV and mortality and nonlinear HRV and mortality were compared for the entire population (ALL), those without coronary artery bypass graft post-MI (no CABG), and those without CABG or diabetes (no CABG, no DIAB) using univariate and multivariate Cox regression analysis. Strength of association was compared by P values and Wald Chi-square values. Nonlinear HRV included short-term fractal scaling exponent, power law slope, and SD12 (Poincaré dimension). For ALL and for no CABG, increased daytime SD12 had the strongest association with mortality (P = 0.002 ALL and P < 0.001 no CABG). For no CABG, no DIAB increased 24-hour SD12 hours had the strongest association (P < 0.001) with mortality. Upon multivariate analysis, increased SD12, decreased ln ULF (ultra low frequency), and history of prior MI and history of congestive heart failure each remained in the model.

Conclusion: Nonlinear HRV is associated with mortality post-MI. However, as with traditional HRV, this is diluted by CABG surgery post-MI and by diabetes. Results suggest that decreased long-term HRV and increased randomness of heart rate are each independent risk factors for mortality post-MI.

(J Cardiovasc Electrophysiol, Vol. 16, pp. 13-20, January 2005)

Keywords: heart rate variability; ambulatory ECG; postmyocardial infarction; risk factors

Document Type: Research article

DOI: 10.1046/j.1540-8167.2005.04358.x

Affiliations: 1: Washington University School of Medicine, St. Louis, Missouri, USA 2: University of Oulu, Oulu, Finland

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Traditional and Nonlinear Heart Rate Variability Are Each Independently Associated with Mortality after Myocardial Infarction