COMPLEX HEART-RATE-VARIABILITY AND SERUM NOREPINEPHRINE LEVELS IN PATIENTS WITH ADVANCED HEART-FAILURE

Objectives. This study was designed to examine the relation of the Poi ncare plot heart rate variability pattern to sympathetic nervous syste m activity as assessed by serum norepinephrine. Background. Poincare p lots demonstrate a complexity of beat to beat behavior not readily det ected by other heart rate variability measures. Previous studies have described two abnormal Poincare patterns in patients with heart failur e: a torpedo pattern with reduced beat to beat variability and a compl ex 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 analyz ed in 21 patients with heart failure (mean left ventricular ejection f raction [+/-SD] 0.22 +/- 0.05). Results. Eleven subjects had a torpedo -shaped and 10 subjects had a complex Poincare 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 var iability. However, patients with a complex Poincare plot pattern had h igher norepinephrine levels (722 +/- 373 pg/ml) than patients with tor pedo-shaped plots (309 +/- 134 pg/ml) (p = 0.003). Patients with a com plex pattern also had more severe hemodynamic decompensation, as evide nced by their higher levels of pulmonary capillary wedge and mean pulm onary artery pressures and lower values for cardiac index than those o f patients with a torpedo-shaped plot. Conclusions. Complex Poincare p lots are associated with marked sympathetic activation and may provide additional prognostic information and insight into autonomic alterati ons and sudden cardiac death in patients with heart failure.