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The microvascular resistance reserve (MRR) is a novel invasive index of the microcirculation, which is independent of epicardial stenoses, and has both diagnostic and prognostic implications. This study investigates whether MRR is associated with health status outcomes by revascularization in patients with moderate coronary stenoses. Consecutive patients with stable chest pain and moderate (30%-90% diameter) stenoses on invasive coronary angiography (n = 222) underwent invasive physiology assessment. Revascularization was performed according to guideline recommendations. At baseline and follow-up, health status and myocardial perfusion were assessed by the Seattle Angina Questionnaire (SAQ) and positron emission tomography. The primary endpoint was freedom from angina at follow-up with secondary endpoints including changes in health status by SAQ domains and myocardial perfusion by MRR and revascularization status. Low MRR was defined as ≤3.0. Freedom from angina occurred in 38/173 patients. In multivariate analyses, MRR was associated with freedom from angina at follow-up (odds ratio 0.860, 95% confidence interval 0.740-0.987). By MRR and revascularization groups, patients with normal MRR who did not undergo revascularization, and patients with abnormal MRR who underwent revascularization, had improved health status of angina frequency mean difference SAQ angina frequency score 8.5 (3.07-13.11) and 13.5 (2.82-23.16), respectively. For both groups, health status of physical limitation mean difference in SAQ physical limitation score 9.7 (4.79-11.93) and 8.7 (0.53-13.88), respectively and general health status mean difference in SAQ summary score 9.3 (5.18-12.50) and 10.8 (2.51-17.28), respectively also improved. Only patients with abnormal MRR who underwent revascularization had improved myocardial perfusion. In patients with moderate coronary stenoses, MRR seems to predict the symptomatic and perfusion benefit of revascularization. NCT03481712 and NCT04707859.
Rasmussen et al. (Sun,) studied this question.