J wave syndromes in patients with spinal and bulbar muscular atrophy

Males with X-linked recessive spinobulbar muscular atrophy (SBMA) are reported to die suddenly and a Brugada electrocardiography (ECG) pattern may be present. A hallmark of this pattern is the presence of ST segment elevations in right precordial leads associated with an increased risk of sudden cardiac death.

We aimed to detect subtle myocardial abnormalities using ECG and cardiovascular magnetic resonance imaging (CMR) in patients with SBMA.

30 SBMA patients (55.7 ± 11.9 years) and 11 healthy male controls underwent 12-lead ECGs were recorded using conventional and modified chest leads. CMR included feature-tracking strain analysis, late gadolinium enhancement and native T1 and T2 mapping.

Testosterone levels were increased in 6/29 patients. Abnormal ECGs were recorded in 70%, consisting of a Brugada ECG pattern, early repolarization or fragmented QRS. Despite normal left ventricular ejection fraction (66 ± 5%), SBMA patients exhibited more often left ventricular hypertrophy as compared to controls (34.5% vs 20%). End-diastolic volumes were smaller in SBMA patients (left ventricular volume index 61.7 ± 14.7 ml/m² vs. 79.1 ± 15.5 ml/m²; right ventricular volume index 64.4 ± 16.4 ml/m² vs. 75.3 ± 17.5 ml/m²). Tissue characterization with T1-mapping revealed diffuse myocardial fibrosis in SBMA patients (73.9% vs. 9.1%, device-specific threshold for T1: 1030 ms).

SBMA patients show abnormal ECGs and structural abnormalities, which may explain an increased risk of sudden death. These findings underline the importance of ECG screening, measurement of testosterone levels and potentially CMR imaging to assess cardiac risk factors.