The concomitant factors implicated in 328 nonfatal decompensations of 304 patients with congestive heart failure were: arrhythmias in 24%, infections in 23%, poor compliance in 15%, angina in 14%, iatrogenic factors in 10%, and other causes in 5% of cases. New York Heart Association class and right atrial pressure significantly related to the occurrence of decompensation. Poor compliance and angina were unpredictable, infection was related to pulmonary wedge pressure, iatrogenic factors were predicted by the more advanced functional classes, whereas arrhythmias were more frequent in patients with renal failure.