Coronary Microvascular Dysfunction and Microvascular Angina: A Systematic Review of Therapies

• Published in: JACC. Cardiovascular imaging Vol. 8; no. 2; pp. 210 - 220
• Main Authors: Marinescu, Mark A, Löffler, Adrián I., Ouellette, Michelle, Smith, Lavone, Kramer, Christopher M., Bourque, Jamieson
• Format: Journal Article
• Language: English
• Published: 01.02.2015
• ISSN: 1936-878X; 1876-7591
• DOI: 10.1016/j.jcmg.2014.12.008

Angina without coronary artery disease (CAD) has substantial morbidity and is present in 10–30% of patients undergoing angiography. Coronary microvascular dysfunction (CMD) is present in 50–65% of these patients. The optimal treatment of this cohort is undefined. We performed a systematic review to evaluate treatment strategies for objectively defined CMD in the absence of CAD. We included studies assessing therapy in human subjects with angina and coronary flow reserve (CFR) or myocardial perfusion reserve (MPR) <2.5 by positron emission tomography (PET), cardiac magnetic resonance imaging (CMR), dilution methods, or intracoronary Doppler in the absence of coronary artery stenosis ≥50% or structural heart disease. Only 8 articles met strict inclusion criteria. The articles were heterogeneous, using different treatments, end-points, and definitions of CMD. Small sample sizes severely limit the power of these studies, with an average of 11 patients per analysis. Studies evaluating, sildenafil, quinapril, estrogen, and transcutaneous electrical nerve stimulation (TENS) application demonstrated benefits in their respective endpoints. No benefit was found with L-arginine, doxazosin, pravastatin, and diltiazem. Our systematic review highlights that there is little data to support therapies for CMD. We assess the data meeting rigorous inclusion criteria and review the related but excluded literature. We additionally describe the next steps needed to address this research gap, including a standardized definition of CMD, routine assessment of CMD in studies of chest pain without obstructive CAD, and specific therapy assessment in the population with confirmed CMD.