Background: Angina in patients without obstructive coronary artery disease (ANOCA) presents with diverse clinical manifestations and leads to a substantial impairment in quality of life, physical performance, and mental health. ANOCA is also linked to a higher risk of adverse cardiovascular events and imposes a considerable burden on patients and healthcare systems due to recurrent medical treatments. Among patients with angina referred for invasive coronary angiography, 50–70% are found to have ANOCA. Coronary microvascular dysfunction (CMD) underlies approximately one quarter of these cases, either as an isolated finding or in combination with other pathologies, with evidence suggesting a higher prevalence in women.
Hypothesis: We hypothesized that a significant proportion of patients with ANOCA have CMD and that the different endotypes of CMD differ between men and women. Furthermore, we expected gender-specific differences in the prevalence and characteristics of CMD, as well as in the severity of symptom burden and disease-specific perception of illness.
Methods: This multicenter registry (MICRO: a Registry Study in Patients With Microvascular Angina, NCT04612322) included 500 patients enrolled between November 2020 and February 2025 across five medical centers in Germany. All participants underwent cardiac catheterization due to suspected coronary artery disease, but angiography revealed no significant coronary obstruction. Subsequently, functional measurement of coronary arteries was performed in all patients, determining numerous parameters, including fractional flow reserve, coronary flow reserve, and the index of microvascular resistances. Hemodynamic parameters were used to determine the underlying endotypes in patients with CMD. In addition to functional measurements, clinical parameters were determined and angina symptom burden, quality of life, and individual perception of the disease were assessed.
Results: Data from 500 patients were included in the baseline analysis. The average age of study participants was 66 years, and 268 participants were women. According to the Canadian Cardiovascular Society (CCS) classification, patients suffered from class II-IV angina, with class III angina being reported most frequently within the female cohort (p<0.0001) and class II angina being most common in the male cohort (p<0.0001). Detailed endotype- and gender-dependent analyses will be presented at the congress.
Conclusions: The results of the study registry will be presented at the main congress as part of detailed analyses of endotype-specific disease manifestations and gender-specific differences in patients with CMD.
