Background Cardiac resynchronisation therapy (CRT) improves morbidity and mortality in heart failure (HF). Impaired endothelial function, as measured by flow mediated dilation (FMD) is associated with increased morbidity and mortality in heart failure (HF) and may help to differentiate responders from non-responders.

Methods FMD was measured at baseline and 12 months following CRT. The patient group were 94% male, mean age 69 ± 8 years, New York Heart Association (NYHA) functional class II-IV, QRSd 173 ± 21 ms and had a left ventricular ejection fraction (LVEF) 26 ± 8%.

Results 70% of patients were found to have responded at 12 months. Responders had significant improvements in VO₂ (12.6   ± 1.7 to 14.7 ± 1.5 ml/kg/min, p < 0.05), quality of life score (43 ± 23 to 24 ± 22, p < 0.01), left ventricular end diastolic volume (210 ± 125 ml to 173 ± 125 ml, p < 0.01), NT-proBNP (2422 ± 829 ml to 1732 ± 976 ml, p < 0.01 and 6 min walk distance (379 ± 117 m at baseline to 418 ± 105 m, p < 0.05). Baseline FMD in responders was 2.9 ± 1.9% and 7.4 ± 3.73% in non-responders (p < 0.05).

Conclusions This confirms that FMD identifies response to CRT, due to endothelium dependent mechanisms alone.