Relationship between coronary microvascular and epicardial spasm at intracoronary acetylcholine testing in patients...

Patients with Angina and unobstructed coronary arteries (ANOCA) frequently suffer from coronary spasm. Intracoronary provocative testing may reveal microvascular and/or epicardial spasm. However, the relationship of these two spasm types has not been investigated systematically.

We enrolled 142 ANOCA patients (mean age 63 years, 44% female) in whom intracoronary acetylcholine testing demonstrated epicardial spasm at the highest acetylcholine dose (i. e. 200 μg) in the left coronary artery according to the COVADIS criteria. In all patients, demographic data, cardiovascular risk factors and procedural data were recorded. The latter included symptoms and/or ischemic ECG shifts during lower acetylcholine doses. This enabled diagnosis of microvascular spasm before documentation of epicardial spasm.

49 out of 142 patients (35%) had microvascular spasm before documentation of epicardial spasm. Thirty-one patients (22%) had an uneventful test and in 62 (43%) the acetylcholine test was inconclusive. Statistical analysis revealed no significant differences between patients with and without microvascular spasm regarding cardiovascular risk factors. However, patients with microvascular spasm were significantly more often female (55% vs. 29%, p = 0.037). Multivariable analysis revealed female sex as significant predictor for the occurrence of microvascular spasm (OR 3.0, 95% CI 1.15-7.80, p = 0.021).

In patients with epicardial spasm microvascular spasm at lower acetylcholine doses can be diagnosed in 35% of ANOCA patients. Independent of cardiovascular risk factors women are affected by this scenario three times more often than men. Our results underline the importance of the coronary microcirculation and sex-specific differences in the pathophysiology of coronary spasm.