Aortic stenosis (AS) is known to result in left ventricular hypertrophy (LVH) and decreased coronary flow reserve (CFR). Danish researchers wondered if CFR in the left descending artery (LAD) would improve following aortic valve replacement. They also sought to explore the relationship between changes in CFR and any corresponding change in left ventricular mass (LVM) and stroke work. They conducted an exploratory study of 34 patients who had undergone a transcatheter aortic valve implantation or replacement procedure.
Investigators measured CFR, absolute hyperaemic coronary flow, and absolute minimal microvascular resistance values before and 6 months after valvular replacement. They also used cardiac magnetic resonance imaging to measure LV anatomy and function, to calculate LVM and LV stroke work.
Comparison of values pre- and post-aortic valve replacement showed that CFR in the left anterior descending artery increased significantly at 6 months. The improved CFR was associated with a decrease in LV stroke work. Additionally, LVM decreased at follow-up, and the index of microcirculatory resistance was unchanged. There was no correlation between LV stroke work and LVM at baseline.
Investigators attributed CFR improvement on the global scale (i.e., without indexing to LVM) to a lowered resting flow. Conversely, they attributed CFR improvement on the regional scale (i.e., after indexing to LVM) to a higher resting flow.
Investigators interpreted that CFR is more closely related to stroke work than to myocardial mass.
The authors concluded that aortic valve replacement can result in improved CFR, regression of LVH, and reduced LV stroke work. Furthermore, investigators acknowledged that their sample size in this study was small. Additionally, they used bolus thermodilution-derived CFR values; however, continuous saline thermodilution-derived values would be preferable as they show less variability.
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Author: Kelly Schoonderwoerd
Original Article: Sabbah M. et al., EuroIntervention 2022 Oct 13.