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. 2023 Feb 20;18(14):1156-1164.
doi: 10.4244/EIJ-D-22-00621.

Long-term changes in coronary physiology after aortic valve replacement

Affiliations

Long-term changes in coronary physiology after aortic valve replacement

Muhammad Sabbah et al. EuroIntervention. .

Abstract

Background: The detrimental effects of long-standing severe aortic stenosis (AS) often include left ventricular hypertrophy (LVH) and exhaustion of coronary flow reserve (CFR), the reversibility of which is unclear after valve replacement.

Aims: Our aims were to 1) investigate whether CFR in the left anterior descending artery (LAD) would improve following valve replacement, and if the change was related to changes in hyperaemic coronary flow (QLAD) and minimal microvascular resistance (Rμ,LAD); and 2) investigate the relationship between changes in CFR and changes in left ventricular mass (LVM) and stroke work (LVSW).

Methods: We measured intracoronary bolus thermodilution-derived CFR, and continuous thermodilution-derived QLAD and Rμ,LAD 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 LVSW. 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 QLAD (230±106 mL/min to 250±101 mL/min; p=0.26) or Rμ,LAD (347 [IQR 247-463] to 287 [IQR 230-456]; p=0.20). When indexed for LVM, QLAD was 39% (IQR 8-98%) higher at follow-up compared with baseline (p<0.001). The improvement in CFR was correlated with ΔLVSW, 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 LVSW.

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Conflict of interest statement

K. Arslani has received a research grant from the Swiss Academy of Medical Sciences and the Bangerter Foundation (YTCR 09/19) and the Swiss National Science Foundation (P500PM_202963) outside of the submitted work. The other authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1. Patient-level changes in hyperaemic flow and microvascular resistance. A) Patient-level changes in hyperaemic blood flow (QLAD) and B) minimal microvascular resistance (Rµ,LAD) in the LAD. LAD: left anterior descending artery; WU: Wood Units
Patient-level changes in hyperaemic flow and microvascular resistance. A) Patient-level changes in hyperaemic blood flow (QLAD) and B) minimal microvascular resistance (Rμ,LAD) in the LAD. LAD: left anterior descending artery; WU: Wood Units
Figure 2
Figure 2. Patient-level changes in CFR.
LAD CFR at 6-month follow-up after aortic valve replacement. CFR: coronary flow reserve; LAD: left anterior descending artery
Figure 3
Figure 3. Baseline and follow-up mean transit times in the LAD.
Box and whisker plot of the changes in resting and hyperaemic mean transit times from baseline to follow-up after aortic valve replacement. The centre line represents the median; the edges of the boxes show the interquartile range; the whiskers represent the minimum and maximum values. LAD: left anterior descending artery
Figure 4
Figure 4. Change in left ventricular stroke index vs change in resting mean transit time.
Association between the change in left ventricular stroke work indexed to body surface area (ΔLVsw,index, x-axis) and the change in resting mean transit time (ΔTmn, y-axis). Results were similar with ΔLVsw. Regression line equation: y= −0.03765x+0.1144, r= −0.42; p=0.03 (Spearman’s rho= −0.56; p=0.002). Dashed lines represent 95% confidence intervals. cJ: centijoule
Figure 5
Figure 5. Change in left ventricular mass index vs change in resting transit mean time.
Association between the change in left ventricular mass index (ΔLVMi) and the change in resting mean transit time (ΔTmn). Regression line equation: y=−9.98∙10−3x–0.01, r= –0.46; p=0.015 (Spearman’s rho= –0.51; p=0.007). Dashed lines represent 95% confidence intervals.
Central illustration
Central illustration. Summary of the changes in left ventricular stroke work, CFR and hyperaemic and resting flow after aortic valve replacement.
Underlying changes mediating the improvement of coronary flow reserve (CFR) in the left anterior descending artery (LAD) following aortic valve replacement. The increase in CFR after valve replacement was driven predominantly by a decrease in global resting flow (Qrest), with little to no change in global hyperaemic flow (Qhyp). However, because left ventricular mass (LVM) was significantly reduced at follow-up, Qhyplt; per gram of myocardium was significantly higher relative to baseline. Thus, valve replacement lowers resting flow and increases regional hyperaemic flow in tandem with regression of left ventricular hypertrophy. Note, Qrest is used here for simplicity, in place of resting mean transit time which was the surrogate for resting flow we measured in the present study. LVsw: left ventricular stroke work

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