The authors examined the prevalence and significance of cardiac rhythm disturbances in healthy elderly individuals. They selected 26 men with active lifestyles, aged 70-81 years, after clinical, routine blood tests, chest radiographs, echocardiography, resting and exercise electrocardiography, and Gated cardiac blood imaging evaluations. The men were submitted to continuous electrocardiographic monitoring during their daily routine. The recording time ranged from 838 to 1,432 min (average = 1,307 +/- 153 min). Clinical follow-up was done every six months. Sinus rhythm predominated in all subjects. The maximal, minimal, and average heart rate ranges (beats/min) were, respectively: during sleeping periods, 60-115 (85.8 +/- 13.2), 42-80 (56.6 +/- 8.7), 51-85 (64.0 +/- 8.8); and during awake periods, 85-150 (118.4 +/- 16.4), 50-85 (64.1 +/- 9.1), 61-90 (75.3 +/- 8.3). The longest sinus pauses were observed during sleep and ranged from 0.8 to 2.5 sec (1.25 +/- 0.34 sec). Atrial ectopic beats were observed in 20 individuals (76.9%). They were frequent in four (15.4%) and repetitive in nine (34.6%) of them. Short-lasting episodes of paroxysmal atrial tachycardia and paroxysmal atrial flutter were observed in one case each. Ventricular ectopic beats were recorded in 20 individuals (76.9%). They were frequent in 6 (23%) and multiform in 13 (50%) of them. Couplets were observed in 5 cases (19.2%) and episodes of nonsustained ventricular tachycardia were present in 3 individuals (11.5%). No symptoms were referred by any individual during recording. No clinical signs of heart disease or symptoms were noticed during the average 40 +/- 7.2 months of follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)