Endothelial dysfunction in heart failure identifies responders to cardiac resynchronization therapy

BackgroundThe presence of endothelial dysfunction is associated with increased heart failure mortality. Cardiac resynchronization therapy (CRT) improves heart failure outcomes; however, current guidelines do not adequately identify responders to CRT.ObjectiveThe purpose of this study was to determine whether endothelial dysfunction can predict response to CRT.MethodsBrachial artery flow-mediated dilation, a measure of endothelial function, was measured at baseline preimplant and 90 days postimplant in 33 patients undergoing CRT (age 64.2 ± 16.8 years, left ventricular ejection fraction [LVEF] 25% ± 9%, QRS duration 158 ± 25 ms, New York Heart Association class III–IV).ResultsOf the 33 patients, 19 (58%) were responders to CRT. Baseline flow-mediated dilation was 4.6% ± 4.5% in responders and 8.6% ± 4.2% in nonresponders (P <.01). After 90 days of CRT, responders had significant improvement in LVEF (23% ± 8% to 30% ± 9%, P = .03), 6-minute walk distance (756 ± 213 feet to 1,089 ± 242 feet, P = .04), and quality of life (52 ± 22 to 31 ± 28, P <.005), whereas nonresponders did not show improvement in these measures. The presence of baseline endothelial dysfunction correlated with impaired baseline functional capacity (r = 0.39, P = .03), and improvement in flow-mediated dilation correlated with improvement in 6-minute walk distance (r = 0.34, P = .05). Logistic regression analysis showed that every 1% reduction in baseline flow-mediated dilation correlated with an approximately 5% increased likelihood of response to CRT. The predictive value of baseline endothelial dysfunction was independent of QRS duration, LVEF, or dyssynchrony and provided additive prognostic value.ConclusionThe presence of endothelial dysfunction independently identifies CRT responders and provides additive prognostic value for predicting response over current criteria. Addition of endothelial function assessment to current selection criteria may improve the ability to identify CRT responders.