Angiotensin II receptor blockers and isolated left bundle branch block: A retrospective cohort analysis.

Chronic left bundle branch block (LBBB) has been associated with adverse cardiac remodeling and the development of cardiomyopathy. This retrospective cohort study evaluated the impact of angiotensin II receptor blocker (ARB) therapy on cardiovascular outcomes in adults with isolated LBBB with no known heart failure (HF), cardiomyopathy, or ischemic heart disease. Using the TriNetX global research network, patients were stratified by ARB use and followed for up to 5 years. Propensity score matching was performed to balance characteristics. Three thousand two hundred sixty-six patients were included in each group with comparable baseline characteristics. The ARB therapy was not associated with a reduction in new-onset acute HF events (4.9% vs 4.4%; hazard ratio (HR) 1.05 (95% CI 0.84-1.32)). Similarly, there were no significant differences in rates of all-cause hospitalizations, cardiac arrest, or ventricular tachycardia. However, ARB use was associated with a significantly lower, all-cause mortality rate (8.6% vs 12.1%; HR 0.67 (95% CI 0.57-0.77)). This is the first real-world study examining ARB use in a cohort with isolated LBBB, highlighting a potential mortality benefit, despite no difference in acute HF risk. While ARBs are not effective in preventing LBBB-induced cardiomyopathy based on these findings, the observed survival advantage warrants further investigation. Prospective studies are needed to elucidate mechanisms underlying this mortality benefit and to determine whether ARBs should be considered in the management of patients with isolated LBBB.