Sympathetic overactivity and sudden cardiac death among hemodialysis patients with left ventricular hypertrophy

Background We prospectively investigated whether cardiac autonomic imbalance is associated with sudden cardiac death (SCD) among a group of hemodialysis patients with left ventricular hypertrophy (LVH). Methods In a prospective cohort study, we enrolled 196 asymptomatic patients on chronic hemodialysis who had LVH as determined by echocardiography and had undergone twenty-four-hour ambulatory Holter electrocardiography between dialysis sessions (males/females, 114/82; mean age, 65±12 years) to analyze heart rate variability. We calculated the percentage difference between adjacent NN intervals more than 50 ms (pNN50) and high-frequency component (HF, 0.15–0.40 Hz) as parameters of cardiac parasympathetic activity, and the low-frequency component (LF, 0.04–0.15 Hz)/HF component ratio as a parameter of sympathetic activity. Results During 4.5±1.9-year follow-up, 21 patients who had undergone coronary revascularization within 60 days of enrollment were excluded from the analysis. Among the remaining 175 patients (male/female, 105/70; 66±12 years), SCD was recognized in 23 patients. On stepwise Cox hazard analysis, SCD was positively associated with age and LF/HF ratio, and tended to be inversely associated with pNN50. On Kaplan–Meier analysis, SCD-free survival rates at 5 years were 29.4% and 98.1% in patients with LF/HF ratios of 1.9 or more and below 1.9, respectively. Conclusions The presence of cardiac sympathetic overactivity may predict the occurrence of SCD in the asymptomatic hemodialysis patients with LVH.