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Abstract Background Patients with ischemia and nonobstructive coronary arteries (INOCA) suffer from a broad range of anginal symptoms that may differ depending on the biologic sex of the patient, the underlying coronary vasomotor disorder, or the type of presentation. Purpose We sought to characterize the symptom description and angina classification of patients referred for invasive coronary function testing (CFT) in the DISCOVER INOCA multicenter registry, stratified by type of presentation (stable vs unstable), biologic sex, and underlying diagnosis, including coronary microvascular dysfunction (CMD), vasospastic angina (VSA), or other disorders such as symptomatic myocardial bridging. Methods DISCOVER INOCA is a prospective, multicenter registry in the United States that includes patients who are referred for clinically indicated coronary angiography and found to have INOCA. All patients underwent protocol-guided angiography, acetylcholine provocation, coronary thermodilution, and intravascular imaging. Symptom characteristics were compared between groups. Results From September 2022 until February 2024, 104 patients were enrolled, 78% were female, and mean age was 57 ± 11 years. The post-procedure diagnosis was CMD in 19%, VSA in 41%, a mixed syndrome in 15%, or other diagnosis in 26%. The average coronary flow reserve (CFR) was 2.9 ± 1.1 in the CMD group and 5.3 ± 3.0 in the VSA group, (p < 0.001). 53% of patients presented with stable angina and 47% with unstable or progressive symptoms. Symptoms included chest pain (89%), chest tightness (42%), chest pressure (39%), shortness of breath (53%), and fatigue (16%), and no significant differences were reported when stratified by diagnostic phenotype. Female patients were more likely to report arm/neck/back/jaw pain (25% vs 5% in men, p = 0.038). Symptom triggers included exertion/activity in 73%, emotional stress in 12%, and resting symptoms in 58%. In female patients 4% reported catamenial symptoms. Of patients with stable angina, the Canadian Cardiovascular Society (CCS) Angina Classification was Grade I in 25%, Grade II in 52%, Grade III in 21%, and Grade IV in 2%. In patients with unstable angina, the Braunwald Angina Classification was Class I in 9%, Class II in 73%, and Class III in 18%. Conclusions Patients with INOCA referred for clinically indicated coronary angiography and CFT were predominantly female and most commonly reported chest pain as a presenting symptom. Female patients were more likely to report arm/neck/back/jaw pain than male patients. Over half of patients reported resting symptoms with no differences between the diagnostic phenotypes (CMD, VSA, or other). The CCS and Braunwald angina classification indicated that most patients had moderate intensity symptoms. Patient-reported outcome measures will be used to systematically categorize the symptom burden in these patients.

The purpose of sympathetic neuronal discharge and the recruitment of neuronal subpopulations for human circulatory homeostasis remains unknown. This study tested the hypothesis that sympathetic neuronal discharge and recruitment patterns regulate neuropeptide Y (NPY) bioavailability. Across baseline and an intravenous dexmedetomidine infusion (α2-adrenergic agonist) sympathetic action potential (AP) frequency and total sympathetic AP clusters were associated with NPY bioavailability. This is the first study to report that sympathetic neuronal discharge and recruitment patterns regulate NPY bioavailability to support circulatory homeostasis in humans.