Coronary Microvascular Dysfunction Independently Contributes to Ischemic Heart Disease: Lancet
South Korea: Researchers have discovered in a prospective study that coronary microvascular dysfunction (CMD) is an important independent contributor to ischemic heart disease, although it frequently coexists with epicardial coronary artery disease.
A large multicentre cohort study published in The Lancet by Joo Myung Lee and colleagues from South Korea provides robust real-world evidence on the prevalence and prognostic significance of CMD among patients undergoing invasive coronary angiography. The study, part of the FLOW-CMD Registry, was conducted across seven tertiary care hospitals and included adults referred for clinically indicated coronary angiography.
Coronary microvascular dysfunction refers to impaired function of the small vessels supplying the heart muscle, which may not be detected through conventional imaging of larger coronary arteries. To evaluate this, the investigators used detailed coronary physiological assessments, including coronary flow reserve and the index of microcirculatory resistance, alongside standard angiographic measures to identify both epicardial coronary artery disease and CMD.
Out of 5,764 screened individuals, 1,003 patients were enrolled in the final analysis.
The study led to the following findings:
- Coronary microvascular dysfunction was observed in 21.5% of patients with obstructive epicardial coronary artery disease.
- CMD was also present in 9.3% of patients without significant epicardial coronary artery obstruction.
- These findings indicate that CMD occurs not only in patients with visible large-vessel disease but also in those without overt epicardial abnormalities.
- Over a median follow-up of लगभग two years, major cardiovascular outcomes assessed included all-cause mortality, myocardial infarction, repeat revascularisation, and heart failure hospitalisation.
- Patients with CMD had a significantly higher risk of adverse cardiovascular events compared to those with preserved microvascular function.
- The estimated two-year event rate was 18.8% in patients with CMD versus 10.5% in those without CMD, indicating nearly double the risk.
The findings show that CMD is an independent predictor of adverse cardiovascular outcomes, even after adjusting for epicardial coronary artery disease, indicating that evaluation of only large coronary vessels may miss an important aspect of ischemic risk.
Conducted across multiple centers with consecutive patient enrollment and standardized protocols, the study closely reflects real-world clinical practice and supports the generalisability of its results.
Overall, the FLOW-CMD Registry underscores that CMD is both common and clinically significant. Early detection may improve risk stratification and enable more targeted treatment strategies to enhance cardiovascular outcomes.
Reference:
Lee, J. M., Lee, S. H., Gim, D. H., Lee, S. Y., Choi, K. H., Ahn, J. H., Hong, Y. J., Kim, H. K., Lee, K. Y., Choo, E. H., Jeon, K., Kim, H., Kang, M. G., Koh, J., Joh, H. S., Park, T. K., Yang, J. H., Song, Y. B., Choi, S., . . . Hahn, J. (2026). Coronary microvascular dysfunction and cardiovascular outcomes (Multicenter FLOW-CMD Registry): A prospective, multicentre cohort study in South Korea. The Lancet. https://doi.org/10.1016/S0140-6736(26)00666-5
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