Baseline intervals in electrocardiogram for risk stratification in Brugada syndrome: A 10-year prospective study

Background: Risk stratification in Brugada syndrome (BrS) remains challenging. The aim of this study was to evaluate the baseline intervals in resting ECG of a cohort of Portuguese patients with first-degree relatives diagnosed with BrS and to identify ECG parameters associated with cardiac events (CE) over a 10-year period. Methods: Prospective study assessing 107 Portuguese patients with first-degree relatives diagnosed with BrS and followed over a decade to detect CE. Subgroups included spontaneous type 1 (SB), inducible type 1 (IB), and normal ECG. CE were a composite endpoint comprising of sudden cardiac death (SCD), implantable cardioverter-defibrillator (ICD) implantation and appropriate ICD shocks. Results: 15% patients with SB and 10% patients with IB, mean age was 29.9 +/- 16 years; 51% were male. SB and IB patients exhibited significantly higher PR intervals than those with normal ECG (p p <0.01, p = 0.02, respectively). There were no differences in PR interval between SB and IB (p p = 0.93). CE occurred in 41.5% of SB and in 18.2% of IB patients. No CE in patients with normal ECG and normal flecainide provocative test. PR interval was an independent predictor of earlier CE (HR 1.06 CI 95% [1.02-1.10]; p <0.01), adjusted to familiar SCD and positive genetic test. Mean time for a CE was significantly shorter in patients with PR >200 ms and the optimal cutoff value for predicting CE was 180 ms. Conclusion: The PR interval is a significant parameter in basal ECG associated with CE in BrS. Considering the PR interval in the design of clinical algorithms is recommended for accurate individual risk assessment.