Importance of Holter monitoring in patients with periodic cerebral symptoms.

Holter monitoring was used in 358 patients with symptoms of intermittent dizziness, blackout, or both. The neurological findings in all patients were normal. None manifested evidence of a pertinent arrhythmia on the one-minute resting ECG; 8.9% of the patients demonstrated arrhythmias known to correlate with cerebral symptoms; and 11.2% demonstrated "predisposing" arrhythmias, ie. rhythms that in and of themselves may not precipitate symptoms but predispose to arrhythmias that do. The latter category included short bursts of ectopic tachycardia and intermittent short-duration asystole. High-frequency ectopic beats were observed in 24.6%. In almost every patient in whom intermittent arrhythmias precipitated symptoms there were many "predisposing" arrhythmias of short duration that occurred during the asymptomatic period. A comparison of 12- and 24-hour recordings demonstrated an increase in pertinent arrhythmias from 13.8 to 22.7%.