The change of angina levels in patients with chronic coronary syndromes and coronary microcirculatory dysfunction - a prospective study with 24 months follow-up.

Introduction: A substantial proportion of patients with chronic coronary syndromes suffer from angina even after medical treatment and revascularization. Coronary microvascular dysfunction (CMD) is discussed as a potential mechanism.

Aim: To assess angina status in patients with chronic coronary syndromes undergoing functional assessment of coronary circulation regarding the presence of coronary microcirculatory dysfunction.

Material and methods: The study included 101 consecutive patients referred for coronary angiography requiring functional stenosis assessment, with median age of 66 years, 74% male, diagnosed or treated for dyslipidemia (91%) and diabetes type 2 (42%), 20% with a history of prior non-ST myocardial infarction. Fractional flow reserve (FFR), coronary flow reserve (CFR), resistive reserve ratio (RRR), and index of microcirculatory resistance (IMR) were measured. The diagnosis of CMD was defined by either IMR ≥ 25 units or CFR ≤ 2.0 in case of no significant stenosis. A change of one CCS class over 24 months follow-up was considered clinically significant.

Results: In patients without CMD diagnosis, there was a significant decrease in angina intensity (p < 0.001). Lack of angina improvement was associated with lower median RRR (2.30 (1.70, 3.30) vs. 3.05 (2.08, 4.10), p = 0.004) and lower median CFR (1.90 (1.40, 2.50) vs. 2.30 (IQR: 1.60, 3.00), p = 0.021), as compared to patients with angina improvement.

Conclusions: The presence of CMD is a risk factor for no angina improvement. Impaired coronary resistive reserve ratio and lower microvascular reactivity may be one of the pathomechanisms leading to the lack of angina improvement in patients with chronic coronary syndromes.