Coronary microcirculation dysfunction causing ischemia with non-obstructive coronary arteries: a case report.

The study presents a case of INOCA attributed to CMVD in a 53-year-old male patient experiencing exertional angina, despite the absence of significant coronary artery stenosis on angiography. The patient presented with reversible myocardial ischemia detected by myocardial perfusion imaging, with an ischemic area accounting for 12% of the left ventricular wall. Diagnostic tests revealed an elevated index of microcirculatory resistance (IMR = 46.3) and a quantitative flow ratio (QFR = 0.94), confirming CMVD. Genetic testing identified a NOTCH1 c.3862G>A variant in the proband and some family members, suggesting a potential contribution to CMVD pathogenesis through impaired vascular remodeling and microcirculatory regulation. After six months of targeted treatment with nicorandil, coenzyme Q10, trimetazidine, and rosuvastatin, the patient's symptoms resolved, and myocardial ischemia reversed. While an MYH7 variant was also detected, its clinical relevance was ruled out due to the family's absence of associated cardiomyopathy phenotypes. The NOTCH1 gene may play a potential role in INOCA caused by CMVD, however, further research is needed to elucidate its underlying regulatory mechanisms. The findings provide a foundation for precise diagnosis and personalized management of INOCA.