24-HOUR AMBULATORY ELECTROCARDIOGRAPHY IN ELDERLY SUBJECTS - PREVALENCE OF VARIOUS ARRHYTHMIAS AND PROGNOSTIC IMPLICATIONS (REPORT FROM THEBRONX LONGITUDINAL AGING STUDY)

Functional, ambulatory, community-dwelling subjects (n = 423, aged 75 to 85 years) underwent baseline 24-hour ambulatory electrocardiography (EGG) examinations as part of the Bronx Aging Study, a 10-year prospe ctive cohort study designed to identify risk factors and disease marke rs for cardiovascular, cerebrovascular, and dementia illnesses in old people. Premature ventricular contractions were the most commonly obse rved arrhythmia noted( 93% of subjects), with a low prevalence of nons ustained ventricular tachycardia (5%), paroxysmal atrial tachycardia ( 13%), atrial fibrillation (4%), and atrioventricular blocks (4%). A 24 -hour sinus rate of <60 beats/min was noted in 13% of subjects, and 11 % of subjects were noted to have transient episodes of severe bradycar dia (<40 beats/min). In a multivariate analysis, nonsustained ventricu lar tachycardia was an independent predictor of death (p = 0.015; rela tive risk [RR] 2.8; 95% confidence interval (CI] 1.4 to 5.8) and myoca rdial infarction (p = 0.031; RR 3.2; CI 1.2 to 9.4). Transient atriove ntricular block was an independent predictor of stroke (p = 0.0006; RR 9.7; CI 3.3 to 28.9), as was sinus bradycardia over a 24-hour period (p = 0.033; RR 2.7; CI 1.2 to 6.4). Ventricular tachycardia approached significance as an independent predictor of multiinfarct dementia (p = 0.052; PR 6.3; CI 1.4 to 28.7). Episodes of paroxysmal atrial fibril lation, atrial tachycardia, and severe bradycardia were not associated with adverse outcomes. Some arrhythmias found on the ambulatory ECG i n very old subjects can predict an increased risk for subsequent death , myocardial infarction, stroke, and multiinfarct dementia.