LONG-TERM PROGNOSTIC-SIGNIFICANCE OF AMBULATORY ELECTROCARDIOGRAPHIC FINDINGS IN APPARENTLY HEALTHY SUBJECTS-GREATER-THAN-OR-EQUAL-TO-60 YEARS OF AGE

To determine the long-term prognostic significance of frequent or complex ectopic beats and ST-segment changes on 24-hour ambulatory electrocardiogram (ECG) in apparently healthy older subjects, 98 volunteers were followed up from the Baltimore Longitudinal Study of Aging who were 60 to 85 years old and free of cardiac disease by history, physical examination and maximal treadmill testing at the time of ambulatory ECG between 1978 and 1980. Over a mean follow-up period of 10 years, coronary events developed in 14 subjects: angina pectoris in 7, nonfatal myocardial infarction in 3 and sudden cardiac death in 4. The incidence of coronary events did not differ significantly between subjects who developed the following arrhythmias and those who did not, respectively: greater-than-or-equal-to 30 supraventricular ectopic beats in any hour, 18 vs 13%; greater-than-or-equal-to 100 supraventricular ectopic beats in 24 hours, 20 vs 12%; paroxysmal atrial tachycardia, 15 vs 14%; greater-than-or-equal-to 30 ventricular ectopic complexes (VECs) in any hour, 17 vs 14%; greater-than-or-equal-to 100 VECs in 24 hours, 18 vs 14%; or repetitive VECs, 20 vs 13%. The mean 24-hour heart rate (75 +/- 8 vs 72 +/- 9 beats/min) as well as the maximal (116 +/- 20 vs 111 +/- 18 beats/min) and minimal (51 +/- 6 vs 53 +/- 7 beats/min) heart rate also did not differ between the coronary event and non-event groups. Although flat or downsloping ST-segment depression greater-than-or-equal-to 1.0 mm was seen in only 5 subjects, coronary events occurred in 2 of these 5 (40%) vs only 12 (13%) of 93 subjects without such ST-segment changes. When 11 additional persons with lesser degrees of ST-segment depression were included, events occurred in 6 of 16 (38%) compared with 8 of 82 (10%) subjects without any ST-segment changes, p <0.05. In 2 of the 3 subjects who died suddenly, both nonsustained ventricular tachycardia and ST-segment depression were present. Thus, neither supraventricular ectopic beats nor simple VEC patterns on ambulatory ECG predict the development of future coronary events in clinically healthy older subjects; ambulant silent ischemia, although infrequent, may be the best predictor of future coronary events in such a population.