First-degree atrioventricular block on basal electrocardiogram predicts future arrhythmic events in patients with Brugada syndrome: a long-term follow-up study from the Veneto region of Northeastern Italy

Aims This study was designed to assess the prognostic value of clinical and electrocardiographic parameters in Brugada syndrome (BrS). Methods and results The study population included 272 consecutive patients (82% males; mean age 4312years), with either a spontaneous (n=137, 50%) or drug-induced (n=135, 50%) Type 1 Brugada electrocardiogram (ECG) pattern. The study combined endpoint included sudden cardiac death (SCD), cardiac arrest, and appropriate intervention of implantable cardioverter-defibrillator (ICD). A first-degree atrioventricular (AV) block (PR=219 +/- 17ms) was documented at basal ECG in 45 patients (16.5%); 27 of these underwent an electrophysiological study with recording in 21 (78%) of an HV interval 55ms (mean 61 +/- 3ms). Patients with first-degree AV block had a wider QRS complex (median 110ms vs. 95ms; P=0.04) and more often showed a left anterior hemiblock pattern (n=13, 29% vs. n=35, 16%; P=0.056). During a mean follow-up of 85 +/- 55months, 17 patients (6.3%) experienced 1 major arrhythmic events (appropriate ICD intervention, n=13 and SCD, n=4). At univariate analysis, the occurrence of major arrhythmic events was significantly associated with a history of syncope or cardiac arrest (P<0.001), Type 1 ECG pattern (P=0.04), and first-degree AV block (P<0.001). Univariate and multivariable predictors of events included a history of syncope or cardiac arrest [hazard ratio (HR) 5.8, 95% confidence interval (95% CI) 2.04-16.5; P<0.001; and HR 6.68, 95% CI 2.34-19.1; P<0.001; respectively], a spontaneous Type 1 ECG pattern (HR 1.56, 95% CI 1.03-4.24; P=0.033; and HR 1.84, 95% CI 1.01-4.29; P=0.044; respectively) and a first-degree AV block at baseline ECG (HR 3.84, 95% CI 1.47-9.99; P=0.006; and HR 4.65, 95% CI 2.34-19.1; P=0.002; respectively). Conclusion Besides a history of cardiac arrest or syncope, first-degree AV block on basal ECG is an independent predictor of malignant arrhythmic events and a stronger marker of arrhythmic risk than a spontaneous coved-type' ECG pattern in patients with BrS.