Abstract Body (Do not enter title and authors here): Background: Invasive coronary reactivity testing (CRT) is the gold standard for comprehensive assessment of coronary endothelial and microvascular dysfunction in patients with angina and non-obstructive CAD (ANOCA). Non-invasive imaging modalities (PET and CMR) have emerged as potential alternatives. However, due to the inability to systemically administer acetylcholine, patients with normal coronary flow reserve (CFR) but abnormal endothelial function on invasive Ach testing are systemically missed on non-invasive testing. We aimed to assess the prevalence of coronary endothelial dysfunction in ANOCA patients with normal CFR.
Methods: Consecutive patients undergoing CRT at our institution were included. Those with normal adenosine-based CFR (>2.5), were further stratified as having normal coronary endothelial function (NEF, <20% epicardial coronary diameter constriction and >50% increase in coronary blood flow in response to ACh) vs abnormal endothelial function (AEF, >20% epicardial coronary diameter constriction and/or <50% increase in coronary blood flow in response to Ach). We then assessed the proportion of AEF patients who would have been otherwise diagnosed with normal coronary physiology based on CFR alone on non-invasive testing.
Results: 37 patients underwent CRT. Mean age was 55 years ± 25, 68% were females. 25 out of 37 patients (68%) had normal CFR. Of those patients, 17 (68%) patients had AEF. Distribution of coronary epicardial vs microvascular endothelial dysfunction is represented in Fig. 1.
Conclusion: 68% of ANOCA patients with normal CFR had coronary epicardial and/or microvascular endothelial dysfunction and would have otherwise been labeled as ‘normal coronary physiology’ by non-invasive microvascular function testing. Our findings re-enforce the need for comprehensive invasive CRT for accurate comprehensive diagnosis of patients with ANOCA.