Vasomotor dysfunction in patients with angina and nonobstructive coronary artery disease is dominated by vasospasm.

BACKGROUND: Coronary vasomotor dysfunction, comprising endotypes of coronary spasm and/or impaired microvascular dilatation (IMD), is common in patients with angina and no obstructive coronary arteries (ANOCA). However, there are discrepant reports regarding the prevalence of these endotypes. The objective of this study was to determine the prevalence of coronary vasomotor dysfunction in patients with ANOCA, underlying endotypes, and differences in clinical characteristics. METHODS: Prospective registry of patients with ANOCA that underwent clinically indicated invasive coronary function testing (CFT), including acetylcholine spasm testing (2-200 µg) to diagnose coronary spasm, and adenosine testing (140 µg/kg/min) to diagnose IMD, defined as an index of microvascular resistance ≥25 and/or coronary flow reserve <2.0. RESULTS: Of the 111 patients that completed CFT (88% female, mean age 54 years), 96 (86%) showed vasomotor dysfunction. The majority 93 (97%) had coronary spasm, 63% isolated and 34% combined with IMD. Isolated IMD was rare, occurring in only 3 patients (3%). Hypertension was more prevalent in patients with vasomotor dysfunction compared to those without (39% vs. 7%, p = 0.02). Obesity and a higher severity of angiographic atherosclerotic disease were more prevalent in patients with coronary spasm compared to those without (61% vs. 28%; 40% vs. 0%, respectively, both p < 0.01). No differences in angina characteristics were observed between patients with and without vasomotor dysfunction or between endotypes. CONCLUSIONS: Coronary vasomotor dysfunction is highly prevalent in patients with ANOCA, especially epicardial or microvascular vasospasm, whereas isolated IMD was rare. Performing a CFT without acetylcholine testing should be strongly discouraged.

Absolute Coronary Blood Flow Measured by Continuous Thermodilution in Patients With Ischemia and Nonobstructive Disease.

BACKGROUND: Intracoronary continuous thermodilution is a novel technique to quantify absolute coronary flow (Q) and resistance (R) and has potential advantages over current methods such as coronary flow reserve (CFR) and index of microvascular resistance (IMR). However, no data are available in patients with ischemia and nonobstructive coronary artery disease (INOCA). OBJECTIVES: This study aimed to assess the relationship of Q and R with the established CFR/IMR in INOCA patients, to explore the potential of absolute Q, and to predict self-reported angina. METHODS: Consecutive INOCA patients (n = 84; 87% women; mean age 56 ± 8 years) underwent coronary function testing, including acetylcholine (ACH) provocation testing, adenosine (ADE) testing (CFR/IMR), and continuous thermodilution (absolute Q and R) with saline-induced hyperemia. RESULTS: ACH testing was abnormal (ACH+) in 87%, and ADE testing (ADE+) in 38%. The median absolute Q was 198 ml/min, and the median absolute R was 416 WU. The absolute R was higher in patients with ADE+ versus ADE- (495 WU vs. 375 WU; p = 0.04) but did not differ between patients with ACH+ versus ACH- (421 WU vs. 409 WU; p = 0.74). Low Q and high R were associated with severe angina (odds ratio: 3.09; 95% confidence interval: 1.16 to 8.28; p = 0.03; and odds ratio: 2.60; 95% confidence interval: 0.99 to 6.81; p = 0.05), respectively. CONCLUSIONS: In this study, absolute R was higher in patients with abnormal CFR/IMR, whereas both Q and R were unrelated to coronary vasospasm. Q and R were associated with angina, although their exact predictive value should be determined in larger studies.