Critical coronary insights: low-threshold testing reduces coronary microvascular dysfunction (CMD) gender differences but CMD's 1-year impact persists

Background Angina pectoris is a common clinical manifestation of ischemic heart disease, yet a significant proportion of patients undergoing coronary angiography (CAG) do not show obstructive coronary artery disease. Patients with Ischemia and Non-Obstructive Coronary Artery disease (INOCA) present a clinical challenge due to persistent symptoms, uncertain prognosis, and high healthcare utilization. Coronary function testing (CFT) is recommended to identify vasomotor dysfunction endotypes and guide targeted treatment. Coronary flow reserve (CFR) and index of microvascular resistance (IMR) are established techniques for detecting coronary microvascular dysfunction (CMD). However, data on the prognosis, healthcare burden, and quality of life of INOCA patients remain limited. Purpose This registry aims to systematically collect data on INOCA patients undergoing low-threshold CFT in the Netherlands, providing insights into their clinical outcomes, treatment responses, and resource utilization. In this specific project, results from patients in the south of the Netherlands that underwent CFT at the Maastricht University Medical Center (MUMC), will be presented. Methods Two groups were analysed at baseline and one-year follow-up: patients with normal CMD measurements and those with abnormal CMD measurements, defined as CFR <2.5 and/or IMR >25. INOCA patients (n= 145; 51% women; mean age 65.7 ± 10.1 years) underwent adenosine (ADE) testing for CFR/IMR with or without spasm provocation testing. Throughout the follow-up period, patients completed questionnaires to assess their clinical status, healthcare utilization, and quality of life. Results ADE testing was abnormal in 38% of the patients (n=55). The median CFR was 3.40 [2.60-5.00] and the median IMR was 17.00 [13.00-25.00]. Abnormal CFR and/or IMR did not differ significantly for men and women (40 vs. 36%, p = 0.620). The prevalence of atrial fibrillation and COPD were higher in the group with an abnormal CFR and/or IMR compared to the group with normal CFT measurements (23.6% vs.11.1% and 14.5% vs. 4.4%, respectively). One year after the CFT, initial symptoms were more present in the abnormal CFR and/or IMR group vs. normal CFR and/or IMR (60% vs. 43.8%, p = 0.007). Moreover, trends regarding a higher need of revascularization procedures and hospitalization for angina pectoris were observed. Conclusions Low-threshold testing showed high prevalence of CMD high (38%) for both men and women. Abnormal CFR and/or IMR patients more often reported persistent symptoms and showed a trend to a higher resource utilization at one year follow-up.Table 1.Baseline Characteristics Table 2.1 Year Follow-Up