1357618 - A pictorial case of COVID-19 related microvascular angina: Multimodality approach to INOCA

A 41-year-old woman presented to cardiology consultation with typical exercise-induced angina (Canadian Class Score I) and dyspnea on exertion (NYHA II). She had no history of known cardiovascular disease or any risk factors. She started to have these symptoms after having a mild COVID-19 infection. Physical examination was unremarkable as well as the ECG and the Echocardiogram. She underwent a treadmill ECG test that showed inferior ST depression of 2 mm at maximal effort (83% of maximal theoretical HR and 5.7 METS) associated with dyspnea.

Diagnostic Techniques and Their Most Important Findings:

Considering the possibility of a false positive result and the low-intermediate pre-test probability of CAD a Coronary Computed Tomography Angiography was ordered that showed minimal non-obstructive plaque. Upon the persistence of the symptoms, the patient underwent a Stress Cardiovascular Magnetic Resonance using Regadenoson. Normal LV and RV cavities with preserved systolic function and absence of LGE were reported.  Interestingly, stress first-pass perfusion images showed a persistent (lasting 6 frames) diffuse subendocardial defect more evident at basal and apical slices. The abnormality resolved completely in rest images. With non-evidence of epicardial CAD, the suspicion of Ischemia with No Obstructive Coronary Artery Disease (INOCA) was raised so an invasive left catheterization with intracoronary physiological assessment was performed. A thermodilution pressure wire was used to estimate the Coronary Flow Reserve (CFR) with adenosine infusion and to calculate the Index of Microvascular Resistance (IMR). The patient was found to have a low CFR of 1.9 (nv >2.5) and a normal IMR of 20 (nv< 25) with no evidence of epicardial or microvascular spams with Acetylcholine infusion. The diagnosis of Coronary Microvascular Functional Dysfunction was documented. Treatment with beta-blocker, ACE inhibitors, statins and cardiac rehabilitation was recommended.

Learning Points from this Case:

INOCA is common in patients with chest pain and non-evidence of obstructive CAD, especially among women who are 3 times more likely to present it. Up to 68% of these patients have evidence of microvascular dysfunction and are at increased risk of major cardiovascular events(Morris et al., 2022).  COVID-19 has been linked to microvascular injury and endothelial dysfunction resulting from direct viral infection or indirectly related to systemic inflammatory and immune responses(Cenko et al., 2021). CMR plays a key role in the non-invasive assessment of ischemia and, thanks to the recent development of quantitative perfusion, in the important differential diagnosis between microvascular vs multivessel balanced ischemia.