Coronary Flow Reserve and Myocardial Resistance Reserve Changes After Transcatheter Aortic Valve Implantation in Aortic Stenosis

Aortic valve stenosis (AS) induces an alteration in hemodynamic conditions that areresponsible for coronary microvasculature impairment. Relief of AS by transcatheter aor-tic valve implantation (TAVI) is expected to improve the coronary artery hemodynamic.We aimed to assess the midterm effects of TAVI in coronary flow reserve (CFR) and myo-cardial resistance reserve (MRR) by a continuous intracoronary thermodilution tech-nique. At-rest and hyperemic coronary flow was measured by a continuousthermodilution technique in 23 patients with AS and compared with that in 17 matchedcontrols, and repeated 6 3 months after TAVI in 11 of the patients with AS. In patientswith AS, absolute coronary flow at rest was significantly greater, and absolute resistanceat rest was significantly less, than in controls (p<0.01 for both), causing less CFR andMRR (1.73<section>0.4 vs 2.85 1.1, p<0.01 and 1.95<section>0.4 vs 3.22 1.4, p<0.01, respectively).TAVI implantation yielded a significant 35% increase in CFR (p>0.01) and a 39%increase in MRR (p<0.01) driven by absolute coronary flow at rest reduction (p = 0.03).In patients with AS, CFR and MRR determined by continuous thermodilution are signifi-cantly impaired. At 6-month follow-up, TAVI improves these indexes and partiallyrelieves the pathophysiologic alterations, leading to a partial restoration of CFR andMRR.(c) 2024 Elsevier Inc. All rights reserved. (Am J Cardiol 2024;214:109-11