PR and QRS intervals in basal electrocardiogram as a useful tool in screening family members for diagnosis of Brugada Syndrome

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Diagnosis of Brugada Syndrome (BrS) requires documentation of a spontaneous or pharmacologically induced type 1 Brugada pattern. In individuals with normal basal electrocardiography, screening methods could be challenging. The aim of the study was to detect if other parameters in basal ECG could be a tool to predict the diagnosis of BrS in family members. Methods Prospective analysis of 78 patients with family history of BrS and referenced for screening. Basal electrocardiogram was performed in all patients. Patients with spontaneous type 1 Brugada pattern in basal ECG were initially excluded. Definitive diagnosis required a presence of a type 1 ECG pattern or conversion of a type 2 to type 1 following provocative test. The Mann-Whitney U test was used for median comparison between groups as univariate analysis. Analysis of the receiver operating characteristic (ROC) curves were performed to evaluate the predictive values of ECG parameters. Results 6% (n=5) had spontaneous type 1 Brugada syndrome. 53% were male (n=41); mean age of 28,9±15,3 years. 31% (n=24) had confirmative diagnosis of BrS. 27% (n=21) were carriers of SCN5A mutation. Mean duration of intervals on basal ECG were: RR 871,2±156,0ms; PR 159,3±34,1ms; QRS 91,4±13,4ms; QTc 404,2±32,0. Syncope occurred in 5% of patients (n=5), 94% were asymptomatic. By univariate analysis the distribution of PR and QRS intervals was significantly different. Wider PR interval was found in patients with BrS (p<0,01) with a median of 200ms (variance of 1269) versus healthy individuals (median of 150ms and variance of 601). Wider QRS intervals were also found in BrS patients compared with healthy individuals (p<0,01) (100ms (288) versus 80ms (204)). The cut-off point, with the most sensitivity (S) and specificity (E) obtained using the Youden index (YI) for PR interval was 170ms (YI 0,5389; Sensitivity (S)≈65% and Specificity(E)≈89%) and for QRS interval was 97ms (YI 0,5148; Sensitivity (S)≈70% and Specificity(E)≈82%). Conclusion Higher PR and QRS intervals were associated with BrS diagnosis comparing to healthy family members which may pose a cost-effective screening tool. More studies are needed to validate this hypothesis.