Complex heart rate variability and serum norepinephrine levels in patients with advanced heart failure

Abstract

Objectives. This study was designed to examine the relation of the Poincaré plot heart rate variability pattern to sympathetic nervous system activity as assessed by serum norepinephrine.Background. Poincaré plots demonstrate a complexity of beat to beat behavior not readily detected by other heart rate variability measures. Previous studies have described two abnormal Poincaré patterns in patients with heart failure: a torpedo pattern with reduced beat to beat variability and a complex pattern with clustering of points.Methods. To assess the relation of these plots to sympathetic activity, plasma norepinephrine at rest and a standard deviation measure of heart rate variability were analyzed in 21 patients with heart failure (mean left ventricular ejection fraction [±SD] 0.22 ±0.05).Results. Eleven subjects had a torpedo-shaped and 10 subjects had a complex Poincaré plot pattern. These two groups did not differ significantly in age, functional class, disease etiology, left ventricular ejection fraction, heart rate, ventricular ectopic activity or in a standard deviation measure of heart rate variability. However, patients with a complex Poincaré plot pattern had higher norepinephrine levels (722 ± 373 pg/ml) than patients with torpedo-shaped plots (309 ± 134 pg/ml) (p = 0.003). Patients with a complex pattern also had more severe hemodynamic decompensation, as evidenced by their higher levels of pulmonary capillary wedge and mean pulmonary artery pressures and lower values for cardiac index than those of patients with a torpedo-shaped plot.Conclusions. Complex Poincaré plots are associated with marked sympathetic activation and may provide additional prognostic information and insight into autonomic alterations and sudden cardiac death in patients with heart failure.