RETRACTED: Diagnosis of Microvascular Angina Using Cardiac Magnetic Resonance

Abstract

BackgroundIn patients with angina and nonobstructive coronary artery disease (NOCAD), confirming symptoms due to coronary microvascular dysfunction (CMD) remains challenging. Cardiac magnetic resonance (CMR) assesses myocardial perfusion with high spatial resolution and is widely used for diagnosing obstructive coronary artery disease (CAD).ObjectivesThe goal of this study was to validate CMR for diagnosing microvascular angina in patients with NOCAD, compared with patients with obstructive CAD and correlated to the index of microcirculatory resistance (IMR) during invasive coronary angiography.MethodsFifty patients with angina (65 ± 9 years of age) and 20 age-matched healthy control subjects underwent adenosine stress CMR (1.5- and 3-T) to assess left ventricular function, inducible ischemia (myocardial perfusion reserve index [MPRI]; myocardial blood flow [MBF]), and infarction (late gadolinium enhancement). During subsequent angiography within 7 days, 28 patients had obstructive CAD (fractional flow reserve [FFR] ≤0.8) and 22 patients had NOCAD (FFR >0.8) who underwent 3-vessel IMR measurements.ResultsIn patients with NOCAD, myocardium with IMR <25 U had normal MPRI (1.9 ± 0.4 vs. controls 2.0 ± 0.3; p = 0.49); myocardium with IMR ≥25 U had significantly impaired MPRI, similar to ischemic myocardium downstream of obstructive CAD (1.2 ± 0.3 vs. 1.2 ± 0.4; p = 0.61). An MPRI of 1.4 accurately detected impaired perfusion related to CMD (IMR ≥25 U; FFR >0.8) (area under the curve: 0.90; specificity: 95%; sensitivity: 89%; p < 0.001). Impaired MPRI in patients with NOCAD was driven by impaired augmentation of MBF during stress, with normal resting MBF. Myocardium with FFR >0.8 and normal IMR (<25 U) still had blunted stress MBF, suggesting mild CMD, which was distinguishable from control subjects by using a stress MBF threshold of 2.3 ml/min/g with 100% positive predictive value.ConclusionsIn angina patients with NOCAD, CMR can objectively and noninvasively assess microvascular angina. A CMR-based combined diagnostic pathway for both epicardial and microvascular CAD deserves further clinical validation.

Different Effects of Vascular Aging on Ischemic Predisposition in Healthy Men and Women

“…Whilst microvascular dysfunction 18,19 is considered in the discussion on predisposition to ischemia in the absence of coronary disease, we propose that our findings suggest that macrovascular (aortic) dysfunction must also be considered. Even in patients with coronary artery disease, large artery stiffness has been shown to predict ischemic threshold.…”

“…Future studies which could build on the work here might also use magnetic resonance imaging or contrast/strain echocardiography to not only incorporate left ventricular dimensions and left ventricular mass but also directly assess for subendocardial ischemia, particularly with stress, to evaluate whether those with more unfavorable SEVR profiles are indeed predisposed to observable subendocardial ischemia with stress. In addition to coronary atheroma burden, microvascular dysfunction 18,19 would be useful to measure in such future studies.…”

Sex-Specific Aspects in the Pathophysiology and Imaging of Coronary Macro- and Microvascular Disease

“…CMR can detect both perfusion defects and obstructive CAD more accurately than invasive Doppler echocardiography and single-photon emission computed tomography (SPECT), respectively [58,64]. It thus offers the potential to diagnose both obstructive CAD and CMD in a single examination [65]. There are no reported sex differences for these imaging methods.…”

Comparison between quantitative cardiac magnetic resonance perfusion imaging and [15O]H2O positron emission tomography

“…With regard to detection of obstructive CAD, quantitative perfusion measures have been shown to be particularly useful in unmasking balanced ischemia due to three-vessel or left main disease and increase conspicuity of subtle (subendocardial) ischemia [21]. In addition, absolute stress MBF and MFR may also provide insight in coronary microvascular function [22]. Although cardiac PET is the commonly used tool for quantitative perfusion imaging, CMR has gained increasing interest for MBF imaging because of its wide availability, high spatial resolution, and non-ionizing nature.…”