Clinical and Prognostic Significance of Idiopathic Left Bundle-Branch Block in Young Adults

Abstract

Aims: LBBB is rare in healthy young adults, and its long-term prognosis is uncertain.

Methods: 56 subjects (aged <50 years), in whom an LBBB was discovered by chance in the absence of clinical and echocardiographic evidence of heart disease, were collected in a multicenter registry.

Results: 69% were males. Mean age at the time of discovery of LBBB was 37 ± 11 years. Mean QRS duration was 149 ± 17 m sec and 35% had left axis deviation. All patients had a normal echocardiogram, except for left ventricular dyssynchrony; 37 patients underwent coronary angiography (30) or myocardial scintigraphy during effort Eriksson and Wilhelmsen (2005), and in all cases obstructive coronary artery disease was excluded. In 2/30 patients who underwent coronary angiography, an anomalous origin of the CX artery from the right coronary sinus was found. Thirty patients underwent cardiac magnetic resonance; in 60% it was normal, while in 40% it revealed late enhancement, which in 33% was localized in the basal septum, suggesting fibrosis of the left bundle branch. During follow-up (12+/10 years, median 10 years) no sudden death occurred. At the end of follow-up, all patients were alive, except for one who suffered accidental death. Two patients (3.5%) underwent PM implantation owing to syncope. The echocardiogram at the end of follow-up revealed LV dysfunction in only one patient.

Conclusions: In young adults without apparent heart disease, LBBB is a heterogeneous condition. In the vast majority of cases, the prognosis is good and no ventricular dysfunction occurs over time. However, as only 18% of our patients were aged >60 years at the end of follow-up, we cannot establish the prognosis in older age-groups.

Figure 1

Male, soccer player. LBBB with left axis deviation discovered by chance at the age of 19 years. An ECG performed 2 years earlier was normal. The echocardiogram was normal. CT coronary angiography (performed at the age of 22 years) shows the left circumflex (CX) artery arising from the right coronary sinus, close to the right coronary artery (RCA). The CX runs back to the aorta.

Figure 2

(a) and (b) Two males, aged 42 (a) and 48 (b) years, with idiopathic LBBB (a and b). In both cases, MRI shows late enhancement in the left posterior septum (arrows), possibly due to fibrosis involving the left bundle. Ao = aorta, RV and LV = right and left ventricles, respectively, RA and LA = right and left atria, respectively.