Appearance of atrial sound after reversion of atrial fibrillation.

To determine the incidence and time of onset of the atrial sound after reversion of atrial fibrillation in patients with myocardial disease, 12 patients with arteriosclerotic heart disease and 4 patients with primary myocardial disease were followed with serial auscultation as well as daily simultaneous apical phonocardiogram, apex cardiogram, and lead II electrocardiogram. Their average age was 52.3 years. Each patient had been in atrial fibrillation for 6 months to 2 years' duration; 13 were reverted to sinus rhythm with DC capacitor discharge and 3 with quinidine sulphate. All 16 patients developed an atrial sound when in sinus rhythm, but only 2 on the day of reversion; the other 14 patients developed an atrial sound on the first to the sixth day after reversion (average third day). The atrial sound persisted in each patient. This study indicates that the atrial sound as a manifestation of diminished ventricular compliance may be absent in patients with myocardial disease immediately after reversion of atrial fibrillation and may later appear as left atrial function improves.