Efficacy of Angiotensin-Converting Enzyme Inhibitors in Coronary Microvascular Dysfunction: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Coronary microvascular dysfunction (CMD) is becoming increasingly recognized as an important contributor to the development of ischemic heart diseases. Without obstructive coronary artery disease, the physiological function of the coronary microcirculation can be altered by structural, functional, and molecular factors, leading to myocardial ischemia. CMD can significantly impact the quality of life and prognosis and imposes a huge financial burden on healthcare systems and people. This meta-analysis aims to investigate the efficacy of angiotensin-converting enzyme inhibitors (ACEIs) for treating CMD. A systematic literature review identified randomized controlled trials (RCTs) comparing ACEIs with placebo in CMD patients. Review Manager, 5.3 for Windows, was utilized. Using the Mantel-Haenszel (M-H) method, improvement in coronary flow reserve (CFR) and systolic blood pressure events was pooled as mean difference (MD) in a meta-analysis model with a fixed effect model, whereas the number of chest pain episodes was pooled as MD with a random effect model. Five randomized controlled trials involving 209 patients were included in the analysis. The analysis demonstrated a statistically significant improvement in CFR in the ACEIs group compared to the placebo group (MD -0.3, 95% CI -0.61 to 0.01, P = 0.05). However, there was no significant difference in the number of chest pain episodes between the ACEIs and placebo groups (MD 1.79, 95% CI -3.99 to 7.58, P = 0.54). Similarly, no significant difference in blood pressure change was observed between the two groups (MD 4.02, 95% CI -3.25 to 11.28, P = 0.28). In conclusion, the appropriate treatment for CMD is a source of contention because adequate data is lacking. Our findings suggest that ACEIs may have a positive effect on improving CFR in patients with microvascular angina. However, ACEIs did not demonstrate a significant impact on the number of chest pain episodes or systolic blood pressure in this patient population. Further research, including RCTs with larger sample sizes and longer follow-up durations, is warranted to provide more conclusive evidence on the role of ACEIs in CMD management.