Predictors of microvascular spasm by spasm provocation testing in patients having angina with no obstructive coronary arteries

Abstract Background Microvascular dysfunction in patients having angina with no obstructive coronary arteries (ANOCA) has been recognized to be associated with poor prognosis, while microvascular spasm (MVS) has not been fully studied due to its diagnostic challenge. Purpose We aimed to explore clinical and coronary physiological characteristics of MVS. Methods We retrospectively studied patients with ANOCA who underwent spasm provocation test (SPT) with intracoronary acetylcholine administration followed by coronary physiological assessment. Epicardial spasm and MVS were diagnosed in accordance with the latest guideline. Physiological indices such as coronary flow reserve (CFR), index of microcirculatory resistance (IMR) and microvascular resistance reserve (MRR) were assessed by bolus thermodilution method using pressure temperature wire in LAD and RCA. Results In a total of 141 patients, 40 (28.4%) patients were diagnosed as epicardial spasm and 22 (15.6%) were diagnosed as MVS according to the diagnostic criteria of the latest guideline. Women was more frequent (63.9% vs 27.3%, P=0.002) and IMR of LAD was significantly higher (34.80 vs 22.95, P=0.005) in patients with versus without MVS. In addition, hypertension tended to be frequent (81.8% vs 60.5%, P=0.089) in patients with MVS. In a multivariable logistic regression analysis, women (odds ratio 5.64 [OR], 95% CI 1.90 – 16.7, P=0.0018) and IMR of LAD (OR 1.02, 95% CI 1.00 – 1.05, P=0.029) were independently associated with the diagnosis of MVS. On the other hand, no clinical characteristics and physiological parameter were significantly associated with epicardial spasm. In a comparison between microvascular and epicardial spasm, women (OR 8.30, 95%CI 2.23 – 30.9, P=0.0016) and IMR of LAD (OR 1.04, 95%CI 1.00 – 1.08, P=0.0462) were still significantly more frequent in MVS patients in multivariable analysis. Conclusion Women and higher IMR of LAD were significantly frequent in patients with versus without MVS, and hypertension tended to be frequent in MVS patients.