INCIDENCE OF SYMPTOMATIC ATRIAL-FIBRILLATION IN PATIENTS WITH PAROXYSMAL SUPRAVENTRICULAR TACHYCARDIA

Objectives. This study was performed to determine the incidence of sym ptomatic, sustained atrial fibrillation in a group of patients with pa roxysmal supraventricular tachycardia. The effects of the mechanism of paroxysmal supraventricular tachycardia (atrioventricular [AV] node r eentry vs. AV reentry through an accessory pathway) and heart rate dur ing the tachycardia on the occurrence of atrial fibrillation were also assessed. Background. There is a substantial incidence of atrial fibr illation in patients with paroxysmal supraventricular tachycardia, but the precise incidence and the factors that determine it are unknown. Methods. One hundred sixty nine patients with paroxysmal supraventricu lar tachycardia were followed up by regular clinic visits and transtel ephonic electrocardiographic monitoring during symptomatic episodes of arrhythmia. The Kaplan-Meier product-limit method was used to estimat e the proportion of patients remaining free of atrial fibrillation dur ing the observation period. The Cox proportional hazards model was use d to assess the effect of mechanism and heart rate during paroxysmal s upraventricular tachycardia on the atrial fibrillation-free period. Re sults. Thirty-two (19%) of the 169 patients had an episode of atrial f ibrillation during a mean follow-up period of 31 months. The cumulativ e percent of patients experiencing an episode of atrial fibrillation w as 6% within 1 month, 9% within 4 months and 12% within 1 year. The me chanism of paroxysmal supraventricular tachycardia was not associated with the time to occurrence of atrial fibrillation; the hazard ratio c orresponding to classification in the AV node reentry group was 0.8 (p > 0.6), The heart rate during paroxysmal supraventricular tachycardia was not associated with the time to occurrence of atrial fibrillation ; the hazard ratio associated with an increase in heart rate of 50 bea ts/min during the tachycardia was 1.15 (p > 0.5). Conclusions. This st udy suggests that atrial fibrillation will develop in similar to 12% o f patients with paroxysmal supraventricular tachycardia during a 1-yea r follow-up period. The occurrence of atrial fibrillation is not relat ed to the mechanism or heart rate of the paroxysmal supraventricular t achycardia.