Predictors of late arrhythmic events after generator replacement in Brugada syndrome treated with prophylactic ICD

Abstract

IntroductionPredictors of late life-threatening arrhythmic events in Brugada syndrome (BrS) patients who received a prophylactic ICD implantation remain to be evaluated. The aim of the present long-term multicenter study was to assess the incidence and clinical-electrocardiographic predictors of late life-threatening arrhythmic events in BrS patients with a prophylactic implantable cardioverter defibrillator (ICD) and undergoing generator replacement (GR).MethodsThe study population included 105 patients (75% males; mean age 45 ± 14years) who received a prophylactic ICD and had no arrhythmic event up to first GR.ResultsThe median period from first ICD implantation to last follow-up was 155 (128–181) months and from first ICD Implantation to the GR was 84 (61–102) months. During a median follow-up of 57 (38–102) months after GR, 10 patients (9%) received successful appropriate ICD intervention (1.6%/year). ICD interventions included shock on ventricular fibrillation (n = 8 patients), shock on ventricular tachycardia (n = 1 patient), and antitachycardia pacing on ventricular tachycardia (n = 1 patient). At survival analysis, history of atrial fibrillation (log-rank test; P = 0.02), conduction disturbances (log-rank test; P < 0.01), S wave in lead I (log-rank test; P = 0.01) and first-degree atrioventricular block (log-rank test; P = 0.04) were significantly associated with the occurrence of late appropriate ICD intervention. At Cox-regression multivariate analysis, S-wave in lead I was the only independent predictor of late appropriate ICD intervention (HR: 9.17; 95%CI: 1.15–73.07; P = 0.03).ConclusionsThe present study indicates that BrS patient receiving a prophylactic ICD may experience late appropriate intervention after GR in a clinically relevant proportion of cases. S-wave in lead I at the time of first clinical evaluation was the only independent predictor of persistent risk of life-threatening arrhythmic events. These findings support the need for GR at the end of service regardless of previous appropriate intervention, mostly in BrS patients with conduction abnormalities.

Delayed depolarization and histologic abnormalities underlie the Brugada syndrome

“…These include first degree atrioventricular (AV) block and prolonged HV interval, S wave in I lead and fragmented QRS complexes (fQRS) 6–8,26–30 . In recent papers, first degree AV block and HV interval ≥55 ms have been deemed as independent predictors of major arrhythmic events 8,39 (Figure 1). As a proof, such findings were also described by the initial works about BrS, all in patients who suffered from aborted SCD or major VA 5–7,43 .…”

“…These include first degree atrioventricular (AV) block and prolonged HV interval, S wave in I lead and fragmented QRS complexes (fQRS). [6][7][8][26][27][28][29][30] In recent papers, first degree AV block and HV interval ≥55 ms have been deemed as independent predictors of major arrhythmic events 8,39 (Figure 1). As a proof, such findings were also described by the initial works about BrS, all in patients who suffered from aborted SCD or major VA. [5][6][7]43 A deep and large S wave in lead I (≥0.1 mV and/or ≥40 ms) is another established predictor of SCD in BrS patient and has been related to a significant conduction delay in the anterolateral RVOT.…”

“…As a proof, such findings were also described by the initial works about BrS, all in patients who suffered from aborted SCD or major VA. [5][6][7]43 A deep and large S wave in lead I (≥0.1 mV and/or ≥40 ms) is another established predictor of SCD in BrS patient and has been related to a significant conduction delay in the anterolateral RVOT. 38,39 Electroanatomic mapping performed in patients with S wave highlighted a longer endocardial activation time, marked delays in the RVOT and low voltage fragmented electrogram in the same region. 38 Of high predictive value for major arrhythmias are also fQRS and epsilon waves, mostly seen in the right precordial leads [40][41][42][43] (Figure 3).…”

Marked PR interval variability in a patient with Brugada syndrome

“…11 In another recent study, the S wave in lead I was the only independent predictor of persistent risk of life-threatening arrhythmic events. 13 The significance of this PR interval variability, with a "harmonic" appearance, is not yet known, as well as its clinical implications.…”

“… 11 In another recent study, the S wave in lead I was the only independent predictor of persistent risk of life-threatening arrhythmic events. 13 …”