[Asystolic pauses in atrial fibrillation. Incidence, dependence on the underlying disease and significance for pacemaker therapy].

The frequency and duration of asystolic pauses in atrial fibrillation was investigated in 100 consecutive patients using 24-hour ECG's obtained by Holter monitoring. Patients were subdivided, according to the length of the maximal RR-interval, into group A (no asystolic pauses over 2 seconds duration), group B (pauses between 2 and 4 seconds) and group C (asystoles over 4 seconds duration). Pauses longer than 2 seconds occurred in 57% of patients, but longer than 4 seconds only in 6 cases. A statistically higher frequency was seen in patients with permanent (78.3%) than in those with paroxysmal (24.5%) atrial fibrillation, and in patients with rheumatic valve disease (82.4%) in comparison with the rest (54.3%). In contrast, pauses over 2 seconds occurred in only 22.2% of general medical ward patients. Up to 50% of all asystoles in groups A and B were registered during the night, whereas a day-night variation for group C was not apparent. No correlation could be demonstrated between dizziness and bradycardic conduction in group A and B, but all patients in group C made such complaints during the monitoring period. Asystoles of up to 4 seconds duration in atrial fibrillation can be regarded as "normal"; longer asystoles must be anticipated particularly in patients with rheumatic valvular disease. It is only here that permanent pacemaker therapy appears to be indicated.