BackgroundWe aimed to investigate the presence and severity of coronary microvascular dysfunction (CMD) in inflammatory bowel disease (IBD) including Crohn disease and ulcerative colitis and to elucidate the influence of surgical resection of the diseased intestines on CMD by assessing coronary flow velocity reserve (CFVR) using transthoracic Doppler echocardiography.Methods and ResultsThirty‐seven patients with IBD (aged 44±15 years; 22 patients with Crohn disease and 15 patients with ulcerative colitis) and 30 controls (aged 46±12 years) were enrolled. For CFVR measurement, coronary flow velocity was recorded at rest and during hyperemia by ADP infusion using transthoracic Doppler echocardiography, and CFVR <2.5 defined CMD. CFVR measurement was repeated before and within 1 year after surgery. CFVR was similarly and significantly lower in patients with Crohn disease and those with ulcerative colitis than controls (Crohn disease: 2.92±1.03 [P<0.05 versus controls], ulcerative colitis: 2.99±0.65 [P<0.05 versus controls], and controls: 3.84±0.75). Multiple linear regression analysis showed that the presence of IBD and baseline hs‐CRP (high‐sensitivity C‐reactive protein) were independently associated with low CFVR among all study participants (β=−0.403 [P=0.001] and −0.237 [P=0.037], respectively). Hyperemic coronary flow velocity significantly improved after surgery only in patients with IBD who had CMD. CFVR significantly improved in patients with IBD who had both CMD and non‐CMD, and the extent of CFVR improvements were greater in patients with CMD than non‐CMD. Multiple linear regression analysis showed that the reduction of hs‐CRP was independently associated with improvement of hyperemic coronary flow velocity and CFVR among all patients with IBD (β=−0.481 [P=0.003] and β=−0.334 [P=0.043], respectively).ConclusionsIBD is associated with CMD, which improved after surgical resection of diseased intestines.