Association of Coronary Microvascular Dysfunction with Lipoprotein (a) levels in Patients with Non-Obstructive Coronary Artery Disease

Coronary microvascular dysfunction (CMD) constitutes an increasingly acknowledged aspect of coronary artery disease. Even though traditional cardiovascular risk factors have been implicated in CMD pathogenesis, data on lipoprotein (a) [Lp(a)] is limited. This cross-sectional study aimed to investigate whether Lp(a) levels are associated with CMD in patients with angina and non-obstructive coronary arteries. Coronary physiology assessment was performed with the standard bolus thermodilution technique, allowing for coronary flow reserve (CFR) and index of microvascular resistance (IMR) estimation. Participants were categorized into three groups based on Lp(a) levels {<30 mg/dl, [30-50) mg/dl and ≥50 mg/dl} as well as into two groups based on the presence of CMD. CMD was defined as CFR ≤ 2.5 and/or IMR ≥ 25. A total of 127 patients were recruited. No significant differences in baseline characteristics were observed between the groups. In unadjusted analysis, no significant associations were found. In multivariable analysis adjusting for age and sex, participants with Lp(a) values ≥ 50 mg/dl displayed a trend for a 4.25 increased CMD risk when compared to participants with Lp(a) values < 30 mg/dl (OR 4.25, CI 0.81-22.28, p=0.087). The same group of patients tended to have lower CFR than controls with Lp(a) < 30 mg/dL, with a median CFR that was 1.05 units lower (p = 0.086). In conclusion, patients with high Lp(a) levels tended to display a higher prevalence of CMD and lower CFR. More studies are needed in order to better elucidate the relationship between Lp(a) and CMD.