Patients With Vasospastic Angina and Microvascular Resistance Have Worse Prognosis

By David Douglas

November 19, 2019

NEW YORK (Reuters Health) - In patients with angina and nonobstructive coronary-artery disease, coexistence of epicardial coronary spasm and increased microvascular resistance (IMR) is associated with worse outcomes, according to Japanese researchers.

About half of patients undergoing diagnostic coronary angiography for angina have no significant coronary artery obstruction suggesting that coronary functional abnormalities could be involved, Dr. Hiroaki Shimokawa of Tohoku University Graduate School of Medicine, in Sendai, and colleagues note in the Journal of the American College of Cardiology, online November 4.

To investigate, the researchers studied 187 patients with a mean age of 63.2 years. The patients underwent IMR index measurement and additional acetylcholine-provocation testing showed that 68% had vasospastic angina (VSA).

Over a median follow-up of about 2.4 years, cardiac events occurred in 10 patients (5.3%). One died and nine were hospitalized for unstable angina. Multivariable analysis revealed that IMR correlated with the incidence of cardiac events (hazard ratio, 1.05; P=0.002).

The researchers divided the participants into four groups according to the presence or absence of VSA and an IMR of less than 18 or 18 or more. The median IMR value was significantly higher in the VSA than in the non-VSA groups. Coronary flow reserve (CFR) values were comparable between groups

Compared with the other groups, Kaplan-Meier survival analysis showed a significantly worse prognosis in the group with both a high IMR and VSA.

The researchers, who have previously demonstrated that Rho-kinase plays a central role in the pathogenesis of coronary spasm, also found that Rho-kinase inhibition by intracoronary fasudil significantly ameliorated IMR only in those patients with high IMR and VSA.

Dr. Viviany R. Taqueti of Brigham and Women's Hospital, Harvard Medical School, in Boston, author of an accompanying editorial, told Reuters Health by email, "Coronary functional abnormalities are very common in patients with angina, even in those without obstructive coronary-artery disease. There is substantial overlap between patients with coronary vasospastic angina (a macrocirculation problem) and coronary microvascular dysfunction."

"In fact," she added, "the patients with vasospastic angina demonstrating the highest risk in this study were actually those with coronary microvascular dysfunction."

She points out in her editorial, "The main finding of this provocative study is that, within the cohort of patients with VSA, only those with increased IMR appeared to be at the greatest risk of events. By contrast, patients with VSA and normal IMR demonstrated essentially no risk, similar to that of patients with no VSA."

Dr. Shimokawa did not respond to requests for comments.

SOURCE: https://bit.ly/2QkeFYz and https://bit.ly/2CMlH0n

J Am Coll Cardiol 2019.

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