Brief Reports

Arrhythmogenic Right Ventricular Cardiomyopathy Underlies Syndrome of Right Bundle Branch Block, ST-Segment Elevation, and Sudden Death

Overlapping characteristics of Brugada syndrome (BrS) and arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) have been reported in recent studies, but little is known about the overlapping disease state of BrS and ARVC/D. A 36-year-old man, hospitalized at our institution for syncope, presented with this overlapping disease state. The electrocardiogram showed spontaneous coved-type ST-segment elevation, and ventricular fibrillation was induced by right ventricular outflow tract stimulation in an electrophysiological study. BrS was subsequently diagnosed; additionally, the presence of epsilon-like waves and right ventricular structural abnormalities met with the 2010 revised task force criteria for ARVC/D. After careful investigation for both BrS and ARVC/D, an implantable cardioverter defibrillator was inserted in the patient. This case revealed 2 important clinical findings: (1) BrS and ARVC/D clinical features can coexist in a single patient, and EPS might be useful for determining the phenotype of overlapping disease (e.g., BrS-like or ARVC/D-like). (2) An overlapping disease state of BrS and ARVC/D can change phenotypically during its clinical course. Therefore, careful examination and attentive follow-up are required for patients with BrS or ARVC/D.

The Brugada syndrome is a rare but well-defined cause of sudden cardiac death. The key underlying abnormality is a decrease in net depolarising current due to a genetic defect, though recent evidence also implicates structural abnormalities in some patients. Diagnosis requires a Brugada-type ECG as well as typical clinical features: such clinical considerations are currently key in guiding risk stratification and hence management. Whilst pharmacological therapies are under investigation, the only intervention with a robust evidence base remains insertion of an implantable cardioverter defibrillator. Further research will be required to allow more effective risk stratification and hence more rational therapy.

A growing body of evidence suggests that the arrhythmogenic substrate underlying Brugada syndrome (BrS) is located in the right ventricular outflow tract (RVOT), and electrophysiological abnormalities recently evidenced most commonly concur in conduction slowing. Also, imaging studies reported wall motion abnormalities of the RVOT in patients with BrS, with a various extent of RV remodeling. However, there are no data regarding a potential relationship between electrophysiological alterations and contraction abnormalities in BrS.

We aimed to assess (1) the potential relationship between contraction delays of the RV quantified by phase analysis of equilibrium radionuclide angiography (ERNA), and the spontaneous ST-segment elevation pattern; and (2) to evidence RV remodeling in patients with BrS.

Seventy patients with BrS and 18 control subjects were included in the study. For the purpose of the study, the spontaneous ST-segment elevation pattern was graded simultaneously to ERNA acquisition. RV contraction delays and amplitude were assessed using multiharmonic phase analysis of ERNA, and ventricular volumes and ejection fraction were assessed using gated blood-pool single photon emission computed tomography.

RVOT contraction was delayed in patients with BrS, and RV contraction heterogeneity increased according to the pattern of ST-segment elevation, without impairment of the amplitude of contraction. RV volumes were greater in patients with BrS compared with control subjects, without impairment of the ejection fraction, whatever the ST-segment elevation pattern or the magnitude of contraction heterogeneity.

In patients with BrS, we found a relationship between RV contraction heterogeneity and ST-segment pattern, providing evidence of a functional modulation of the arrhythmogenic substrate.

Previous studies have demonstrated an overlap between the arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) and Brugada syndrome (BS). Conduction delay in the right ventricle has been demonstrated in both entities.

This study investigated specific ARVC/D electrocardiographic (ECG) markers in subjects with spontaneous or drug-induced type 1 ECG pattern of BS.

The study population consisted of 47 apparently healthy individuals (38 men, mean age 44.1 ± 13.3 years) with spontaneous (n = 17) or drug-induced (n = 30) type 1 ECG phenotype of BS. The clinical records of these individuals were retrospectively analyzed.

Fifteen subjects (31.9%) were symptomatic, with a history of syncope. A family history of BS or sudden cardiac death was reported in 10 (21.3%) and 8 (17.0%) cases, respectively. Epsilon-like waves in leads V1-V3 were observed in 6 subjects (12.7%). Epsilon-like waves were seen in spontaneous type 1 ECGs in 2 cases and after sodium channel blocking test in 4 cases. In baseline ECGs, localized prolongation (>110 ms) of the QRS complex in leads V1-V3, QRS duration ratio in (V1+V2+V3)/(V4+V5+V6) ≥ 1.2, and prolonged S wave upstroke (>55 ms) in leads V1-V3 were seen in 48.8%, 29.8%, and 40.4% of subjects, respectively. Epsilon-like waves and delayed S wave upstroke were more commonly observed in subjects with family history of BS (P = .014 and P = .038, respectively).

Specific ECG markers that reflect ventricular conduction delay in ARVC/D are commonly observed in subjects with spontaneous or drug-induced type 1 ECG pattern of BS as well. These depolarization abnormalities may be related to subtle underlying structural abnormalities.