The Holter monitor, the most frequently used diagnostic test in patients with syncope, is nondiagnostic in over 90% of cases. This study sought to determine the impact of a new noninvasive device, the cardiac loop electrocardiographic (ECG) recorder, after Holter monitoring in 57 patients with unexplained syncope. All patients underwent a standardized evaluation protocol and wore the monitor for up to 1 month. In 14 patients, loop recording definitively determined whether an arrhythmia was the cause of symptoms (diagnostic yield 25%; 95% confidence intervals 14 to 38%). Diagnoses included unsuspected ventricular tachycardia (1 patient), high grade atrioventricular block (2 patients), supraventricular tachycardia (1 patient), asystole or junctional bradycardia from neurally mediated syncope (3 patients) and normal cardiac rhythms (the remaining 7 patients). Follow-up of all patients diagnosed as having nonarrhythmic syncope by loop recording showed that none of these patients died suddenly. Cardiac loop ECG recording is an important new diagnostic test in patients with syncope unexplained by Holter monitoring.
Bibliographical noteFunding Information:
From the Divisions of General Internal Medicine and Cardiology, Department of Medicine, and the Division of Biometry, Department of Community and Family Medicine, Duke University Medical Center, Durham, North Carolina. This study was supported in part by grants from the Charles A. Dana Foundation, the Duke Women’s Auxiliary, and grants HL24920, HL40392 and the Biomedical Research Grant Program (S07RR05405) from the National Institutes of Health, Bethesda, Maryland. This study was performed through the General Clinical Research Center (M-01, RR-30) at Duke University Medical Center. Monitoring equipment for this study was provided by Instromedix, Inc., Beaverton, Oregon. Research costs for patients undergoing monitoring with the Ring of Hearts recorder were also provided by Instro-medix, Inc. Manuscript received January 22, 1990; revised manuscript received March 16,1990, and accepted March 2 1.