Microvascular angina ‘an important global problem’
Microvascular angina is a significant health problem that confers risk for major adverse CV events, according to registry data from the Coronary Vasomotor Disorders International Study, or COVADIS, Group.
"Microvascular angina is an under-researched area, partly because no definite universal definition was available before the COVADIS definition and partly because cardiologists are mainly interested in the large coronary arteries but not the smaller vessels that are also part of the coronary circulation. The former are easily visible by coronary angiography, whereas the latter are not,” Hiroaki Shimokawa, MD, PhD, vice dean of the graduate school at the International University of Health and Welfare in Narita, Japan, and emeritus/visiting professor at Tohoku University Graduate School of Medicine in Sendai, Japan, said in a press release.
“Currently, many doctors are not aware of the importance of coronary microvascular dysfunction. As a result, many patients with microvascular angina are misdiagnosed as having postmenopausal disorders or an imbalance of conscious and unconscious nervous system, for instance,” Shimokawa said in the release. “However, previous research has suggested that the number of patients with microvascular angina is 3 [million] to 4 million in U.S., which is equal to or greater than the number of patients with breast cancer, so it is an important global problem.”
The study included 686 patients with microvascular angina (mean age, 61 years; 64% women) from 14 institutions in seven countries who were followed from July 2015 to December 2018.
Researchers found that among the cohort, 59% had objective evidence of myocardial ischemia during noninvasive stress testing.
Invasive assessments of coronary microvascular function were performed in 89% of patients. In that group, 42% had microvascular spasm, 35% had impaired coronary flow reserve, 14% had abnormal microvascular resistance and 6% had slow-flow abnormalities.
According to the researchers, there were 78 major adverse CV events in the overall cohort, including 63 hospitalizations during the median follow-up period of 398 days. The annual incidence of the primary composite of major adverse CV events in the overall cohort was 7.7% per patient year.
The most frequent major adverse event was hospitalization for unstable angina (5.9% per patient year), whereas the rate of CV death was 1% per patient year and the rate of nonfatal MI was 0.5% per patient year, according to the researchers.
There was no significant difference by sex in the incidence of major adverse CV events (6.4% for men vs. 8.6% for women, per patient year; P = .19), the researchers wrote, noting there were also no differences by race/ethnicity after propensity matching.
Independent predictors of major adverse CV events included hypertension (adjusted HR = 1.692; 95% CI, 1.067-2.681; P = .03) and previous CAD (aHR = 2.032; 95% CI, 1.312-3.147; P = .001), Shimokawa and colleagues wrote.
“Our international study demonstrates the importance of coronary microvascular dysfunction in patients with microvascular angina. Considering the fact that coronary microvascular dysfunction is involved not only in microvascular angina but also in other forms of cardiovascular disease, including large coronary artery disease and myocardial disease, we believe clinicians should pay closer attention to it,” Shimokawa said in the release.