Atrial fibrillation and coronary microvascular dysfunction-A clinical signal

Coronary microvascular dysfunction (CMD) is increasingly recognized as a cause of angina in patientswith or without epicardial coronary artery disease. Emerging evidence suggests a pathophysiologic relationship between CMD and atrial fibrillation (AF), but few studies have evaluated this association using invasive microvascular assessment.

We performed a single-center, retrospective analysis of prospectively collected data of consecutive patients undergoing clinically indicated invasive assessment of coronary microvascular function between November 2019 and January 2025. All patients underwent invasive coronary angiography with physiological assessment in the left anterior descending artery, including fractional flow reserve (FFR), coronary flow reserve (CFR), index of microvascular resistance (IMR), and resistive reserve ratio (RRR). CMD was defined by the presence of at least one abnormal parameter: CFR <2.5, IMR >25, or RRR <3.5. AF was defined as a documented history of atrial fibrillation in medical records prior to the procedure, classified as paroxysmal, persistent, or permanent.

CMD was present in 219/422 patients (52%; median age 69 years; 55% female). AF was more prevalent in CMD vs. non-CMD patients (13% vs. 6%, p = 0.019). Among the 42 patients with AF, 30 (71%) had paroxysmal, 5 (12%) persistent, and 7 (17%) permanent AF; persistent or permanent AF was more common in CMD patients with AF (38% vs. 8%). In multivariable analysis, AF was independently associated with CMD (adjusted OR 2.19, 95% CI 1.07-4.63, p = 0.031), along with older age and ischemic heart disease. CMD patients with AF had higher LV filling pressures, reduced RV systolic function, and larger left atrial volume index.

AF is independently associated with CMD, with a higher prevalence of persistent/permanent AF among CMD patients. These findings suggest a bidirectional relationship warranting further investigation in larger prospective cohorts.