Evaluation of non-invasive imaging parameters in coronary microvascular disease: a systematic review

Abstract

Background Coronary microvascular dysfunction (CMD) is an important underlying cause of angina pectoris. Currently, no diagnostic tool is available to directly visualize the coronary microvasculature. Invasive microvascular reactivity testing is the diagnostic standard for CMD, but several non-invasive imaging techniques are being evaluated. However, evidence on reported non-invasive parameters and cut-off values is limited. Thus, we aimed to provide an overview of reported non-invasive parameters and corresponding cut-off values for CMD. Methods Pubmed and EMBASE databases were systematically searched for studies enrolling patients with angina pectoris without obstructed coronary arteries, investigating at least one non-invasive imaging technique to quantify CMD. Methodological quality assessment of included studies was performed using QUADAS-2. Results Thirty-seven studies were included. Ten cardiac magnetic resonance studies reported MPRI and nine positron emission tomography (PET) and transthoracic echocardiography (TTE) studies reported CFR. Mean MPRI ranged from 1.47 ± 0.36 to 2.01 ± 0.41 in patients and from 1.50 ± 0.47 to 2.68 ± 0.49 in controls without CMD. Reported mean CFR in PET and TTE ranged from 1.39 ± 0.31 to 2.85 ± 1.35 and 1.69 ± 0.40 to 2.40 ± 0.40 for patients, and 2.68 ± 0.83 to 4.32 ± 1.78 and 2.65 ± 0.65 to 3.31 ± 1.10 for controls, respectively. Conclusions This systematic review summarized current evidence on reported parameters and cut-off values to diagnose CMD for various non-invasive imaging modalities. In current clinical practice, CMD is generally diagnosed with a CFR less than 2.0. However, due to heterogeneity in methodology and reporting of outcome measures, outcomes could not be compared and no definite reference values could be provided.

A Reminder That Stress Echocardiography Is Useful in Diagnosing Myocardial Ischemia in Nonobstructive Coronary Artery Disease: Case Series

“…Surely, even though our understanding of MVD coronary disease has certainly improved, we still recognize the need for better, more reliable, and reproducible measurements that will aid in improving prognostication and treatment plans [8]. This is clearly relevant, particularly when MVD and the resultant perception of angina not only represents a huge diagnostic dilemma but also creates a significant degree of uncertainty with regard to diagnosis, particularly when adverse events are known to occur in both female and male patients [9,10]. In addition, the diagnosis can become challenging since MVD can exist in the setting of both obstructive and nonobstructive coronary disease [8][9][10].…”

“…This is clearly relevant, particularly when MVD and the resultant perception of angina not only represents a huge diagnostic dilemma but also creates a significant degree of uncertainty with regard to diagnosis, particularly when adverse events are known to occur in both female and male patients [9,10]. In addition, the diagnosis can become challenging since MVD can exist in the setting of both obstructive and nonobstructive coronary disease [8][9][10]. Even in the absence of a clearly defined definitive pathophysiologic basis, a combination of factors including endothelial dysfunction, coronary spasm, inflammation, and atherosclerosis can all disrupt myocardial blood flow by combining potentially structurally abnormal atherosclerotic coronary arteries with vasomotor disorders causing dynamic coronary arteriolar alterations [3,5].…”

“…Based on these principles, current tools used in the assessment of coronary MVD include the administration of vasodilating medications such as adenosine for the measurement of coronary flow reserve invasively; assessment of myocardial perfusion reserve using contrast echocardiography, Doppler echocardiography, or CT perfusion; cardiac MRI or positron emission tomography (PET) [ 5 , 10 ]. However, of these, PET is associated with the most prognostic data at present and it would be considered the test of choice [ 5 , 10 ]. Obviously, factors such as expertise, radiation exposure, cost concerns, and limited availability dictate which test is finally performed.…”

“…It is our belief that the lack of either myocardial perfusion or strain imaging during SE could still be valuable for identifying MVD [ 13 , 18 ], particularly if a less than hyperdynamic wall contractility response is seen at peak stress. In fact, we should be mindful that a hyperdynamic response was the original definition of a normal response to stress and it should remain the basis of all our SE interpretations [ 9 , 10 ]. Certainly, many would undoubtedly argue that this subjective interpretation is operator-dependent as it truly appears to be an interpretation that is not derived or determined by any objective means.…”

Vasomotor Dysfunction in Patients with Ischemia and Non-Obstructive Coronary Artery Disease: Current Diagnostic and Therapeutic Strategies

“…Therefore, no definite cut-offs/reference values could be provided. Probable reasons for this wide divergence include the inconsistency of the reference standard used; the researchers not always being blinded to the values of this reference standard; and the use of different types and doses of vasoactive agents to induce hyperemia [ 59 ].…”