(VP090) REGIONAL CHANGES IN MYOCARDIAL OXYGENATION IN WOMEN WITH ANGINA AND NON-OBSTRUCTIVE CORONARY ARTERY DISEASE

Background: Women with angina and non-obstructive coronary artery disease (ANOCA) are an increasingly recognized group with a heightened risk for cardiovascular events. The pathophysiology for ischemic symptoms in ANOCA may be related to alterations in microvascular structure and function, yet non-invasive diagnostic tests are not available. We examined the use of Oxygenation-Sensitive Cardiovascular MRI (OS-CMR) using vasoactive breathing maneuvers, to assess global and regional changes in myocardial oxygenation in women with ANOCA.

METHODS AND RESULTS: We recruited women (40-65 years) with a history of angina responsive to nitroglycerin in the absence of clinical evidence for nonischemic causes. All women underwent invasive coronary angiography to exclude obstructive coronary artery disease (≥50% stenosis in any epicardial coronary artery). An aged match cohort of women without any history of cardiovascular disease was recruited from the community. Using a clinical 3-T magnetic resonance imaging scanner, OS-CMR image sets were acquired before and immediately after paced-cadence monitored hyperventilation, as well as over a subsequent prolonged breath hold. End-systolic OS-CMR signal intensity was measured at baseline and at the time point closest to 30 seconds of breath hold. Global changes were expressed as a percentage change from baseline (mean and standard deviation (SD) in % change in signal intensity (SI)). We assessed regional variability by measuring intersegmental differences (median and range in % change in SI) along radial, circumferential, and longitudinal directions (Figure 1).

Fifty-four women with ANOCA (mean age: 55 +/- 6.2 years) and forty-eight women without a history of cardiovascular disease (mean age: 51.2 +/- 4.8 years) were recruited. There was no significant difference in CMR parameters of volume, function, or mass and in global myocardial oxygenation between cases and controls (mean % change in SI: 4.94 (+/- 7.3) vs. 4.49 (+/- 10.1), p = 0.82). However, women with ANOCA had statistically significantly higher regional variations in myocardial oxygenation in circumferential (median % change in SI: 5.1 (2.0-7.6) vs. 2.2 (1.4-3.5), p = 0.004) and longitudinal directions (median % change in SI: 11.4 (5.4-16.7) vs. 6.0 (3.0-7.0), p = 0.001). There were no significant differences in radial heterogeneity (median % change in SI: 2.4 (1.4-4.1) vs. 1.9 (0.7-3.1)).

Conclusion: Heterogeneous myocardial oxygenation may explain the presence of ischemic symptoms in the absence of epicardial coronary artery disease. Regional variations in myocardial oxygenation on OS-CMR could serve as an important diagnostic marker for microvascular dysfunction in patients with ANOCA.