BACKGROUND:
Left Anterior Fascicular Block (LAFB) occurs frequently among the elderly, and have a correlation with coronary artery disease (CAD), yet controversies regarding its clinical significance still remain.

METHODS:
We carried on a retrospective study involving 92 LAFB and 478 non-LAFB patients, in which anatomic, clinical and electrocardiographic characteristics were compared.

RESULTS:
LAFB subjects had more pathological CAD (66.3% vs 54.6%, P = 0.039), myocardial infarction (MI) (53.3% vs 37.9%, P = 0.007) and myocarditis (5.4% vs 1.7%, P = 0.043). Among the LAFB group, 58.1% of patients with CAD and 30.2% of patients with MI were clinically misdiagnosed, while 42.9% of patients with MI were clinically missed. Logistic regression showed CAD had no independent relevance with LAFB. LAFB subjects displayed heavier hearts [(451.1 ± 101.3)g vs (407.1 ± 102.3)g, P <  0.001], thicker left ventricular walls [(1.6 ± 0.4)cm vs (1.4 ± 0.3)cm, P = 0.001]. Kaplan-Meier survival analysis indicated significant differences in long-term survival time (χ2 = 12.223, P <  0.001) and cardiac mortality (χ2 = 20.982, P <  0.001) between LAFB and non-LAFB group. Cox multivariate analysis demonstrated LAFB was an independent risk factor of all-cause death (HR = 1.552, 95% CI = 1.208-1.994, P = 0.001) and cardiac death (HR = 2.287, 95% CI = 1.545-3.386, P <  0.001). The major death cause of LAFB was cardiac death (46.7%), including more MI (28.3% vs 13.4%, P = 0.008), myocarditis (4.3% vs 1.0%, P = 0.042) and cardiac rupture (6.7% vs 1.9%, P = 0.022).

CONCLUSIONS:
LAFB subjects had more pathological CAD and MI, but LAFB was not an independent relevant factor of CAD. LAFB lowered the accuracy to clinically diagnose CAD. LAFB patients gained heavier hearts, thicker left ventricular walls, and suffered increased risk of death and cardiac death.





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