Long-term changes in coronary physiology after aortic valve replacement.

We measured intracoronary bolus thermodilution-derived CFR, and continuous thermodilution-derived Q and R before and 6 months after aortic valve replacement. Cardiac magnetic resonance imaging was used to quantify left ventricular anatomy and function for the calculation of LVM and LV.  Results: Thirty-four patients were included (17 patients had transcatheter aortic valve implantation; 14 had surgical valve replacement with a bioprosthesis and 3 with a mechanical prosthesis) who underwent invasive assessment in the LAD. CFR increased from 2.5 (interquartile range [IQR] 1.5-3.3) at baseline to 3.1 (IQR 2.2-5.1) at follow-up (p=0.005), despite no significant change in Q (230±106 mL/min to 250±101 mL/min; p=0.26) or R (347 [IQR 247-463] to 287 [IQR 230-456]; p=0.20). When indexed for LVM, Q was 39% (IQR 8-98%) higher at follow-up compared with baseline (p<0.001). The improvement in CFR was correlated with ΔLV, r= -0.39; p=0.047.   Conclusions: CFR in the LAD increased significantly at follow-up although global hyperaemic flow and minimal microvascular resistance remained unchanged. Thus, a decrease in resting flow was the cause of CFR improvement. CFR improvement was associated with reduction in LV.