Angiography derived assessment of the coronary microcirculation: is it ready for prime time?

ABSTRACT

Introduction

Non-obstructive coronary arteries (NOCA) are present in 39.7% to 62.4% of patients who undergo elective angiography. Coronary microcirculation (<400 µm) is not visible on angiography therefore functional assessment, invasive or noninvasive plays a prior role to help provide a more personalized diagnosis of angina.

Area covered

In this review, we revisit the pathophysiology, clinical importance, and invasive assessment of the coronary microcirculation, and discuss angiography-derived indices of microvascular resistance. A comprehensive literature review over four decades is also undertaken.

Expert opinion

The coronary microvasculature plays an important role in flow autoregulation and metabolic regulation. Invasive assessment of microvascular resistance is a validated modality with independent prognostic value, nevertheless, its routine application is hampered by the requirement of intravascular instrumentation and hyperemic agents. The angiography-derived index of microvascular resistance has emerged as a promising surrogate in pilot studies, however, more data are needed to validate and compare the diagnostic and prognostic accuracy of different equations as well as to illustrate the relationship between angiography-derived parameters for epicardial coronary arteries and those for the microvasculature.

KEYWORDS:

• Coronary microvascular
• angina with non-obstructive coronary artery
• ischemia with non-obstructive coronary artery
• index of microvascular resistance
• angiography

Article highlights

• NOCA is present in one-third to two-thirds of patients who undergo elective angiography.

• Functional assessments of the coronary microcirculation in NOCA patients may help personalize the diagnosis and therefore the treatment strategy.

• The angiography-derived index of microvascular resistance is an emerging angiography-derived measure of the coronary microvasculature, whilst larger studies are required for further validation.

Disclosure statement

Patrick Serruys declares consulting fees from Philips/Volcano, SMT, Xeltis, Novartis, and Merillife. Shengxian Tu declares grants and consultancy from Pulse Medical. Johan H.C. Reiber is CSO at Medis Medical Imaging. Other authors declare no potential conflict of interest related to this work.

Reviewer disclosure

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

J Zhou declares scholarship from Chinese Scholarship Council (202106210330). PW Serruys declares consulting fees from Philips/Volcano, SMT, Xeltis, Novartis, and Merillife. N Kotoku declares a research grant from Fukuda Foundation for Medical Technology. S Tu declares consultancy and grants from Pulse Medical.