April 16th, 2013
Small Study Links Left Anterior Fascicular Block to AF and CHF
In people without known cardiovascular (CV) disease the presence of left anterior fascicular block (LAFB) has not been thought to indicate increased risk. Now a research letter published in JAMA finds evidence that elderly people with LAFB are more likely to die and to develop atrial fibrillation (AF) and congestive heart failure (CHF) than people without LAFB.
The authors speculated that LAFB may be a marker for left heart fibrosis, which is a substrate of AF and CHF. They then examined the long-term outcomes of 1,664 participants without overt CV disease enrolled in the Cardiovascular Health Study (CHS). Of these, 39 patients had LAFB at baseline. After a median followup of 15.7 years and adjustment for baseline differences and risk factors, the LAFB patients had significantly increased risk for AF (HR 1.89, CI 1.11-3.24, p = .02), CHF (HR 2.43, CI 1.44-4.12, p = .001) and death (HR, 1.57, CI 1.08-2.26, p = .02). The authors ruled out progression of conduction disease as a cause because none of the LAFB patients went on to develop LBBB and after 10 years only two required a pacemaker.
The authors concluded that “LAFB may be a clinically relevant marker of an individual’s propensity to left heart fibrosis.” They acknowledged that “it remains possible that LAFB is simply a marker of undetected underlying hypertension or coronary disease.”