Isolated LAFB and outcome

A small study followed up an older cohort of patients with isolated left anterior fascicular block on their ECG (isolated left axis deviation), without clinically manifest cardiovascular disease.

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LAFB was associated with an increased risk of atrial fibrillation, heart failure and death. LAFB is caused by conduction tissue fibrosis, and is a marker of other left heart fibrosis. The patients did not go on to develop left bundle branch block, and only 2 of 39 required pacing in 10 years, suggesting these outcomes were not due to progression of conduction disease.

Long-term Outcomes of Left Anterior Fascicular Block in the Absence of Overt Cardiovascular Disease
JAMA. 2013 Apr 17;309(15):1587-8