Coronary physiology: no complete diagnosis without acteylcholine

Abstract Introduction In up to 40% of patients with pectanginous symptoms, no obstructive coronary artery disease (NOCAD, no stenosis > 50%) can be detected as the cause, so that the terms ANOCA (angina with no obstructive CAD) or INOCA (ischemia with no obstructive CAD) have been defined. In patients with acute myocardial infarction, 5-20% are diagnosed with MINOCA (myocardial infarction with no obstructive CAD). Microvascular dysfunction (CMD) or coronary spasm has been identified as one of the leading causes of these entities. Further clarification by determining the coronary flow reserve (CFR) an microvascular resistance (IMR) is used to diagnose CMD and is also included in the ESC guidelines. The indices can be determined using thermodilution or ultrasound/doppler wires methods. According to current recommendations, the acteylcholine provocation test is administered in cases of suspected coronary spasm. Despite extensive studies on the safety of ACh testing, many clinics refrain from testing for vasoconstriction disorder although microvascular coronary spasm has been shown to be the leading subgroup of CMD in registry studies. Purpose We want to investigate the necessity of a complete coronary physiological examination, consisting of CRF/IMR and ACh provocation test, when compared to testing without ACh. Methods All 299 patients who underwent complete physiological testing in our clinic between 2021 and 2024 due to ANOCA, INOCA or MINOCA were evaluated retrospectively. Patients completed a coronary physiological examination using thermodilution and an acetylcholine provocation test. The IMR, CFR, fractional flow reserve (FFR), resting full-cycle ratio (RFR) and the ACh test (defined as epicardial spasm >90% reduction in coronary diameter with symptoms and/or ischemic electrocardiographic changes, respectively no epicardial spasm >90% reduction in coronary diameter with symptoms and and ischemic electrocardiographic changes for microvascular spasm) are thus routinely measured. Results Of the total of 299 patients included, 244 (81%) were found to have impaired vasoconstriction with pathologic ACh testing, either alone or in combination with pathologic indices CFR/IMR. The leading finding of pathological spasms was microvascular coronary spasm (66%). 119 patients with normal CFR/IMR had a diagnosis of microvascular (72 patients) or macrovascular spasm (47 patients). 40% of the total patient cohort would have not had a compete diagnosis without the use of Ach testing. Conclusion Physiological testing without the systematic use of ACh testing will misdagnose a significant amout of patients with ANOCA/MINOCA/INOCA. ACh testing should be always performed to complete the diagnosis for these patients