Arrhythmias in the elderly patients: Atrial fibrillation

Abstract

Aging significantly increases the incidence of atrial fibrillation (AF) and premature contractions. Analysis of ECG recorded on approximately 240,000 subjects who had medical health check for the past 10 years, showed that the incidence of AF was significantly higher in the elderly population of more than 70 years in age (2.5% for men and 0.3% for women) than in younger population. In a study of a smaller clinical cohort of elderly patients with AF, the three major underlying diseases were valvular, hypertensive, and ischemic heart disease, and 10% of patients showed no clinically recognizable heart disease (lone AF). Analysis of pulse Doppler tracings of mitral inflow velocity suggested that LV compliance decreased with aging in healthy men. This finding suggests that AF imposes greater hemodynamic burden on the elderly than the younger population, even if no significant heart disease exists. In patients with paroxysmal AF, the response of heart rate (HR) to treadmill exercise was remarkably greater in AF than in sinus rhythm, and this hyperresponsiveness of HR seems to be responsible for shorter exercise time observed in AF. Although digitalis alleviated the excessive response of HR to exercise and significantly improved exercise tolerance, the in-exercise HR seemed to be still inadequately high in many AF patients. A single oral dose of verapamil (80 mg) or diltiazem (60-90 mg) was shown to further suppress the in-exercise HR and prolong treadmill exercise time in AF patients on maintenance doses of digitalis. However, β-blockers on a similar test schedule showed no significant improvement in exercise tolerance in spite of marked suppression of HR. Additional use of these CA antagonists to digitalis was considered as an effective regimen for control of in-exercise HR in AF. Of 432 patients with acute cerebrovascular accident studied with brain CT, AF was significantly more frequent in 340 patients with cerebral infarction (18.8%) than in 95 with cerebral hemorrhage (2%). In another cohort of 72 consecutive patients with acute cerebrovascular accident studied with cerebral angiography, the incidence of AF was 2.7% in 37 patients with cerebral hemorrhage, 20.7% in 29 with cerebral thrombosis, and 80% in 5 with cerebral embolism, being significantly higher in cerebral embolism than in the former two. In a study population of 102 patients with cerebral embolism confirmed by cerebral angiography, AF was observed in 73 patients (71.6%), of whom 23 had lone AF. These our observations indicate that cerebral embolism is intimately related to AF and suggest that even lone AF can be the cause of systemic embolism. Detection of patients with high risk of cerebral embolism and its prevention are the urgent clinical problem in the management of AF patients.