Relation of arrhythmias and electrolyte abnormalities to survival in patients with severe chronic heart failure.

To investigate the determinants of mortality in patients with chronic congestive heart failure, we prospectively evaluated 84 patients with this disorder who underwent detailed biochemical, clinical, and functional tests at the time of initial evaluation and were then followed for 12 to 52 months (mean 31). During this period of follow-up, 58% of the patients died, of whom 71% died suddenly. The most important pretreatment predictor of mortality in these patients was the frequency of ventricular extrasystoles, followed by echocardiographic fractional shortening, a diagnosis of coronary artery disease, and duration of treadmill exercise. The finding of hypokalemia and hyponatremia in these patients at the time of entry into the study was associated with a poor prognosis by univariate analytical methods, but these electrolyte abnormalities did not provide independent prognostic information. The presence of ventricular arrhythmias was related to the severity of left ventricular dysfunction, exercise intolerance, and neurohormonal activation, suggesting that such arrhythmias are multifactorial in origin and may not simply be related to electrolyte abnormalities.