The role of intracoronary physiology measurements and acetylcholine provocation testing in patients with INOCA. First data from Latvia

Abstract Introduction For diagnosis of exact INOCA endotype the invasive measurements of coronary flow reserve (CFR), index of microvascular resistance (IMR), which both represents the microvascular function, and acetylcholine (ACH) provocation test to diagnose vasospasm is mandatory. Purpose To perform the intracoronary physiological testing, including measurements of CFR, IMR and ACH provocation test for defining the INOCA endotypes – microvascular angina (MVA), vasospastic angina (VSA), microvascular spasm (MVS), or combination of them. Methods The invasive examination was performed in a single University Hospital from March 2023 till December 2023 in patients presented with cardiac symptoms, significant ischemic signs at exercise ECG test and non-obstructed epicardial coronary arteries during invasive or computed tomography coronary angiography (epicardial stenosis less than 50% and/or fractional flow reserve (FFR) 0.80). The criteria for MVA were CFR ≤ 2.5 and IMR ≥ 25. The VSA was assessed if significant (90%) vasospasm occurred during ACH provocation test with subsequent ischemic signs in ECG and chest pain during the test. In patients presented with the ischemic signs in ECG and chest pain during the ACH provocation test, without vasospasm – the MVS was defined. Results Invasive functional testing was performed for 20 patients. 15 patients (75.0%) were women. The mean age of the patients was 59.9 ± 9.4 years. The most common cardiac symptoms were chest pain (18, 90.0%), dyspnea (15, 75.0%), fatigue (14, 70.0%), headache (8, 40.0%) and excessive sweating (6, 30.0%). 3 (15.0%) patients were current or ex-smokers. Dyslipidemia was present in 20 (100.0%), arterial hypertension in 17 (85.0%) and type 2 Diabetes mellitus (T2DM) in 3 (15.0%) patients. In 8 (40.0%) patients the somatoform autonomic dysfunction was suggested as a primary diagnosis after the first tests. 3 patients (15.0%) showed normal values of all measurements. 8 (40.0%) patients were diagnosed with MVA, 6 (30.0%) with VSA, MVS was assessed in 1 (5.0%) patient and the combination of MVA and VSA was observed in 2 (10.0%) cases. Conclusion The first clinical data of INOCA diagnostics of patients in Latvia are very promising since the amount of INOCA patients is high. The patients are underdiagnosed and remains symptomatic without tailored medical treatment, emphasizing that every INOCA endotype requires different treatment. More clinical evidence will be needed to routinely adapt coronary function testing during invasive management.