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. 2023 Feb 27;16(4):470-481.
doi: 10.1016/j.jcin.2022.12.012.

Microvascular Resistance Reserve to Assess Microvascular Dysfunction in ANOCA Patients

Annemiek de Vos  1 , Tijn P J Jansen  2 , Marcel van 't Veer  3 , Aukelien Dimitriu-Leen  2 , Regina E Konst  2 , Suzette Elias-Smale  2 , Valeria Paradies  4 , Laura Rodwell  5 , Stijn van den Oord  2 , Pieter Smits  4 , Niels van Royen  2 , Nico Pijls  3 , Peter Damman  2
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Free article

Microvascular Resistance Reserve to Assess Microvascular Dysfunction in ANOCA Patients

Annemiek de Vos et al. JACC Cardiovasc Interv. .
Free article

Abstract

Background: Microvascular resistance reserve (MRR) is a new index to assess coronary microvascular (dys)function, which can be easily measured invasively using continuous thermodilution. In contrast to coronary flow reserve (CFR), MRR is independent of epicardial coronary disease and hemodynamic variations. Its measurement is accurate, reproducible, and operator independent.

Objectives: The aim of this study was to establish the range of normal values for MRR and to determine an optimal cutoff point.

Methods: In this exploratory study in 214 patients with angina and no obstructive coronary artery disease, after excluding significant epicardial disease, all physiological parameters, such as fractional flow reserve, index of microvascular resistance, CFR, absolute blood flow, absolute microvascular resistance, and MRR, were measured. On the basis of concordant positive or concordant negative results of index of microvascular resistance and CFR, subgroups of patients were defined with high probability of either normal (n = 122) or abnormal (n = 24) microcirculatory function, and MRR was studied in these groups.

Results: Mean MRR in the "normal" group was 3.4 compared with a mean MRR of 1.9 in the "abnormal" group; these values were significantly different between the groups. MRR >2.7 ruled out coronary microvascular dysfunction (CMD) with a certainty of 96%, whereas MRR <2.1 indicated the presence of CMD with a similar high certainty of 96%.

Conclusions: MRR is a suitable index to distinguish the presence or absence of CMD in patients with angina and no obstructive coronary artery disease. The present data indicate that an MRR of 2.7 virtually excludes the presence of CMD, while an MRR value <2.1 confirms its presence.

Keywords: ANOCA; absolute coronary blood flow; coronary physiology; coronary function test; microcirculatory resistance; microcirculatory resistance reserve.

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Conflict of interest statement

Funding Support and Author Disclosures Drs Damman and van Royen have received consulting fees and research grants from Philips. Drs van Royen and Elias-Smale have received a research grant from Abbott. Dr Pijls has received institutional research grants from Abbott and Hexacath; is a consultant for Abbott and Opsens; holds minor equity interest in Philips, ASML, HeartFlow and GE; is member of the scientific advisory board for HeartFlow; and has patents pending on diagnostic methods for quantifying aortic valve stenosis and microvascular physiology. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.

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