Intermittent ventricular standstill during chronic atrial fibrillation in patients with dizziness or syncope.

Thirty-two patients with atrial fibrillation and normal ventricular rates who complained of dizziness or loss of consciousness underwent 24-hour ambulatory electrocardiographic monitoring. A control group of 25 patients in atrial fibrillation but without symptoms of dizziness or loss of consciousness was likewise investigated. All patients remained in atrial fibrillation; periods of ventricular standstill (mean, 2.9; range, 1.8-8.0) were present in 31 symptomatic patients but in only three of the control patients (mean, 1.9 s; range, 1.7-2.4). Twenty-three symptomatic patients with pauses greater than or equal to 2.0 s received a demand pacemaker. Following pacing, nineteen became completely asymptomatic; four patients continued to have dizziness but three of these, who also experienced syncope, no longer did so (mean follow-up, 13 months; range, 6-30). It is suggested that ventricular standstill may commonly occur in patients with controlled atrial fibrillation who complain of dizziness or syncope and that the majority will benefit from permanent cardiac pacing.