Clinical and Physiological Predictors of Acetylcholine‐Induced Coronary Spasm in ANOCA/INOCA Patients: A Retrospective Cohort Study

BACKGROUND: A substantial proportion of patients with angina and/or ischemia are found to have non-obstructive coronary arteries (ANOCA/INOCA). Their symptoms can sometimes be explained by coronary microvascular dysfunction and/or vasospasm. Selecting patients for acetylcholine testing remains challenging, and the procedure is not trivial in terms of logistics, cost, and risk. AIMS: The aim of this single-center retrospective study was to identify predictors of coronary spasm and define features that may help avoid unnecessary testing. METHODS: All consecutive ANOCA/INOCA patients who underwent intracoronary acetylcholine testing between February 2022 and June 2025 at a tertiary university hospital were included. Baseline clinical variables were analyzed using multivariable logistic regression. A 3-variable exploratory model was then constructed to identify independent predictors of unnecessary acetylcholine testing. RESULTS: Among the study population (n = 47), 46.8% demonstrated a positive spasm response. In the multivariable model, age ≥ 60 years (OR = 0.11, 95% CI [0.02-0.80]; p = 0.029) and dyslipidaemia (OR = 0.12, 95% CI [0.01-0.99]; p = 0.049) were independently associated with lower odds of spasm, whereas IMR ≥ 25 showed a non-significant association with lower odds of spasm (OR = 0.10, 95% CI [0.005-1.9]; p = 0.128). The 3-variable exploratory model showed good discrimination (AUC 0.83, 95% CI 0.68-0.97) and was associated with a reduction in overall ACh testing by 45.2% in complete-case analysis, with a sensitivity of 85.7%. CONCLUSIONS: Dyslipidaemia and age ≥ 60 years are independently associated with lower odds of acetylcholine-induced spasm. This model showed good discrimination and may help inform strategies to reduce unnecessary acetylcholine testing, although these findings require external validation.