Fascicular conduction disturbances after coronary artery bypass surgery: a review with a meta-analysis of their long-term significance

Abstract

Fascicular conduction abnormalities are frequently reported following adult cardiac surgery, but their pathogenesis and long-term outcomes remain unclear. In this article, we review the epidemiological features, pathogenesis, diagnosis, and management, and the short-term and long-term significance of fascicular conduction abnormalities following coronary artery bypass graft (CABG) surgery, based on data from 30 studies. Conduction disturbances have an incidence of 3.4% to 55.8% after CABG surgery, the most common being right bundle branch block (RBBB). RBBB is usually transient and benign. Although a slew of factors have been implicated in the pathogenesis of fascicular conduction disturbances, the two most important factors are myocardial ischemia and type of cardioplegia. While a 12-lead electrocardiogram is the gold standard for diagnosis, additional tests such as myocardial enzymes or echocardiography may have additional diagnostic and prognostic value. Short-term prognosis after RBBB is good, but its impact on long-term survival is unclear. We conducted a meta-analysis, the first of its kind in this area, using long-term survival data from five studies. There was no difference in long-term survival between patients who developed conduction disturbances after CABG surgery, and those who did not, indicating a benign influence of conduction disturbances on long-term survival, and the lack of the necessity for monitoring or pacing. While the older literature reported an adverse impact of fascicular conduction disturbances on long-term survival, the more recent studies report a substantially reduced mortality after CABG surgery, despite a higher incidence of conduction disturbances, pointing to the effect of improved surgical techniques.