[Establishment of permanent atrial fibrillation and time course of the amplitude of the f wave].

Atrial fibrillation is one of the arrhythmias that increase with increasing age. In this study we compared transition intervals from sinus rhythm to permanent atrial fibrillation and the time course of the f wave amplitude immediately after the transition between 32 younger (less than 65 years) and 44 elderly patients (greater than or equal to 65 years) in whom transition from sinus rhythm to permanent atrial fibrillation was confirmed on serial ECG recordings. Each group was classified into three categories according their underlying diseases: hypertensive heart disease, valvular disease, and lone atrial fibrillation. In patients with hypertensive heart disease or lone atrial fibrillation, there was no significant difference in the transition intervals between the younger and the elderly groups. In both groups the transition intervals were significantly (p less than 0.05) longer in patients with lone atrial fibrillation than those in patients with hypertensive heart disease (44.6 vs. 12.5 months in younger and 26.8 vs. 12.9 months in elderly). A significant positive correlation (r = 0.58, p less than 0.01) was observed between the final P wave and the initial f wave amplitude on establishment of permanent atrial fibrillation in all patients. In the younger group, the initial f wave amplitude of patients with valvular disease (0.27 +/- 0.04 mV, mean +/- SE) was significantly larger than those of patients with hypertensive heart disease (0.15 +/- 0.03 mV, p less than 0.05) and of patients with lone atrial fibrillation (0.16 +/- 0.01 mV, p less than 0.05). The f wave amplitude of valvular disease was significantly decreased after 1 year (0.22 +/- 0.03 mV, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)