Background: The diagnostic yield of Holter monitoring in patients with syncope is variably reported to be between 6%-20%. This study was done to define predictors of arrhythmic events during the second day of Holter monitoring in patients whose first day Holter recording was normal.
Methods and results: Two serial 24-hour Holter recordings were obtained in a consecutive series of 100 patients (49 patients with unexplained syncope and/or pre-syncope and 51 patients with palpitation). The age of patients was 53.4 +/- 16.9 years and 51 were men. Seventy-six patients had underlying heart disease. Main electrocardiographic findings were found in 40 (40%) patients including non-sustained ventricular tachycardia in 19, sinus pause in 13, symptomatic bradycardia in 5, paroxysmal atrial fibrillation in 4, sustained supraventricular tachycardia in 2, and Mobitz type II second-degree atrioventricular block in 3 patients. Twenty-seven (27%) patients had 33 main electrocardiographic findings during the first day and 13 out of the remaining 73 patients (17.8%) had it during the second day of Holter recording. Presenting symptom (syncope/pre-syncope), age > 65 years, and male gender were significantly associated with increased likelihood of main electrocardiographic findings during the second day of Holter monitoring (p = 006, 0.023, and 0.024, respectively). The risk of main electrocardiographic findings ranged from 5% in patients with one or no predictor to 35% in those with > or = 2 predictors (OR = 9.95, 95% CI = 2.01-49.2, p = 0.002).
Conclusions: Presenting symptom (syncope/pre-syncope), age > 65 years, and male gender increased the likelihood of main electrocardiographic findings during the second day of Holter monitoring.