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Background— Aortic valve stenosis (AS) induces compensatory alterations in left ventricular hemodynamics, leading to physiological and pathological alterations in coronary hemodynamics. Relief of AS by transcatheter aortic valve implantation (TAVI) decreases ventricular afterload and is expected to improve microvascular function immediately. We evaluated the effect of AS on coronary hemodynamics and the immediate effect of TAVI. Methods and Results— Intracoronary pressure and flow velocity were simultaneously assessed at rest and at maximal hyperemia in an unobstructed coronary artery in 27 patients with AS before and immediately after TAVI and in 28 patients without AS. Baseline flow velocity was higher and baseline microvascular resistance was lower in patients with AS as compared with controls, which remained unaltered post-TAVI. In patients with AS, hyperemic flow velocity was significantly lower as compared with controls (44.5±14.5 versus 54.3±18.6 cm/s; P =0.04). Hyperemic microvascular resistance (expressed in mm Hg·cm·s −1 ) was 2.10±0.69 in patients with AS as compared with 1.80±0.60 in controls ( P =0.096). Coronary flow velocity reserve in patients with AS was lower, 1.9±0.5 versus 2.7±0.7 in controls ( P <0.001). Improvement in coronary hemodynamics after TAVI was most pronounced in patients without post-TAVI aortic regurgitation. In these patients (n=20), hyperemic flow velocity increased significantly from 46.24±15.47 pre-TAVI to 56.56±17.44 cm/s post-TAVI ( P =0.003). Hyperemic microvascular resistance decreased from 2.03±0.71 to 1.66±0.45 ( P =0.050). Coronary flow velocity reserve increased significantly from 1.9±0.4 to 2.2±0.6 ( P =0.009). Conclusions— The vasodilatory reserve capacity of the coronary circulation is reduced in AS. TAVI induces an immediate decrease in hyperemic microvascular resistance and a concomitant increase in hyperemic flow velocity, resulting in immediate improvement in coronary vasodilatory reserve.

Background-Myocardial injury is a common complication during cardiac surgery and percutaneous coronary intervention and is associated with postprocedural cardiovascular morbidity and mortality. Limited data have been reported about the occurrence of myocardial damage associated with transcatheter aortic valve implantation (TAVI). Therefore, our purpose was to investigate the incidence, predictors, and prognostic value of myocardial injury during TAVI. Methods and Results-We studied 119 patients (aged 81Ϯ8 years; 47 male) who had undergone a TAVI with the Medtronic-CoreValve bioprosthesis. Serum creatine kinase-MB (CK-MB) and cardiac troponin T (cTnT) levels were measured before and after the procedure. Myocardial injury was defined as a postprocedural increase of CK-MB and/or cTnT level Ͼ5 times the upper reference limit. After TAVI, the incidence of myocardial injury was 17%, which was independently predicted by procedural duration (in minutes) (odds ratio