Identification of electrocardiographic risk markers for the initial and recurrent episodes of ventricular fibrillation in patients with Brugada syndrome

Abstract

Introduction: New onset of ventricular fibrillation (VF) in asymptomatic patients with Brugadatype ECG is not frequent, but it cannot be negligible. Risk markers for predicting VF are usually based on results of analysis in symptomatic patients, and they have not been determined for asymptomatic patients. We analyzed ECG markers in patients with Brugada syndrome to differentiate the risk factors for VF in both symptomatic and asymptomatic patients. Methods:The subjects were 471 patients with Brugada syndrome and we divided the subjects into two groups: Asymptomatic group (n = 326) and Symptomatic group (syncope: n = 122, VF: n = 23). We analyzed the following ECG markers: RR, PQ, QRS, QT and Tpeak-Tend (Tpe) intervals, ST level, atrial fibrillation (AF), atrioventricular block, spontaneous type 1 ECG, early repolariza- tion (ER) and fragmented QRS (fQRS).Results: During follow-up (91 ± 64 months), 41 patients experienced VF (Asymptomatic: n = 10, Symptomatic: n = 31). Univariable analysis showed that spontaneous type 1 ECG, Tpe interval (≥95 milliseconds), high ST level (≥0.52 mV) and fQRS were common predictors for VF in both the Asymptomatic and Symptomatic groups. In addition to the common risk factors, wide QRS (≥107 milliseconds), long QT interval (≥420 milliseconds), ER and AF were predictors for VF in Symptomatic group. Multivariable analysis of the Symptomatic group showed fQRS, Tpe and ER were independent predictors of prognosis.Conclusions: fQRS and Tpe interval are common risk factors for VF in both asymptomatic and symptomatic patients, whereas ER is a predictor for recurrent VF.

Tpeak‐Tend, Tpeak‐Tend/QT ratio and Tpeak‐Tend dispersion for risk stratification in Brugada Syndrome: A systematic review and meta‐analysis

“…Recently, Mugnai and colleagues in a total of 448 subjects found no significant differences T peak ‐T end intervals, (T peak ‐T end )/QT ratio or T peak ‐T end dispersion between patients with VT/VF requiring anti‐tachycardia pacing or with sudden death, and those who were asymptomatic . Similarly, in a separate population of 471 subjects, Morita and colleagues found no significance difference in T peak ‐T end intervals between patients with syncope or VT/VF and asymptomatic patients . Publication of these two studies prompted us to conduct this meta‐analysis, which confirms the value of T peak ‐T end interval, (T peak ‐T end )/QT ratio and T peak ‐T end dispersion, in distinguishing high‐risk patients from low‐risk patients.…”

“…Morita and colleagues also found in 471 patients no difference in T peak -T end intervals between patients with syncope or VT/VF and those who were asymptomatic. 8 These findings contrast with a meta-analysis published previously by some members of our group, which extracted and pooled odds or hazard ratios for the relationship between T peak -T end and arrhythmic and/or mortality outcomes in various clinical conditions, including Brugada Syndrome. 9 This demonstrated prolonged T peak -T end interval was associated with an increased risk of ventricular arrhythmias and SCD in Brugada Syndrome.…”

“…They found no statistically significant difference in all three indices between asymptomatic subjects and patients with syncope and malignant arrhythmias. Morita and colleagues also found in 471 patients no difference in T peak ‐T end intervals between patients with syncope or VT/VF and those who were asymptomatic . These findings contrast with a meta‐analysis published previously by some members of our group, which extracted and pooled odds or hazard ratios for the relationship between T peak ‐T end and arrhythmic and/or mortality outcomes in various clinical conditions, including Brugada Syndrome .…”

“…A total of 29 and 57 entries were retrieved from PubMed and Embase, respectively. Nine studies met the inclusion criteria and were included in our final meta‐analysis . In this meta‐analysis, a total of 1740 subjects with Brugada Syndrome were included (mean age 45 years old, 80% male).…”

“…Therefore, the lower percentage of patients with adverse events can be explained by the lower percentage of Type 1 Brugada patients (21% vs 28%‐100% in the remaining studies) and lower percentage male patients (61% vs 72%‐100%) despite similar percentage with SCN5a positive status (22% vs 13%‐50%). While these differences in patient characteristics affect the likelihood of adverse events occurring, they should not explain the lack of difference in T peak ‐T end intervals between event‐positive and event‐negative groups in the Morita study or the Mugnai study. Interestingly, Mugnai and colleagues found a non‐statistically significant lower T peak ‐T end intervals in event‐positive groups.…”