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Aim Real-world data on use of invasive coronary function testing (CFT) to diagnose ischaemic mechanisms in the presence of refractory angina and non-obstructed coronary arteries (R-ANOCA) is lacking. We performed a retrospective analysis of patients with R-ANOCA undergoing CFT to evaluate clinical characteristics, classification of ischaemic endotypes and changes in CCS class after implementation of treatment stratified by CFT results.Methods A retrospective analysis was performed of patients referred to a single tertiary refractory angina centre between September 2022-December 2020 undergoing CFT. Clinical demographics, medications, non-invasive test results and symptom status were ascertained from electronic health records. CFT consisted of continuous and/or bolus thermodilution for coronary microvascular dysfunction (CMD), +/- intracoronary acetylcholine for vasospasm +/- dobutamine for myocardial bridge assessment, performed at the discretion of the operator. Follow-up analysis was restricted to patients with a confirmed ANOCA endotype and clinical follow-up for >3 months. Data was collected and analysed using Excel and GraphPad (Version 10.4.0).Results 128 patients were included (61M; 67F). Median age was 61 (IQR 14.5) and median BMI was 28 (IQR 7.77). Cardiovascular risk factors were common: hypertension 64%, dyslipidaemia 87%, smoking (ex/current) 32% and diabetes mellitus 20%. 38% of patients had successful previous PCI. Most patients were either on single (74%) or dual (17%) anti-platelet therapy. Cardiovascular risk-modifying therapy was common (lipid-lowering 85%, ACEi/ARB 53%, glucose-lowering 20%), as was baseline anti-anginal therapy (>1 anti-anginal drug 70%, >2 anti-anginal drugs 41%, >3 anti-anginal drugs 20%) most commonly calcium channel blockers (56%), ranolazine (46%) and oral nitrates (45%).CMD was diagnosed in 58/127 patients, vasospasm in 39/61 patients, and significant myocardial bridging in 3/8 patients. 56% of patients were diagnosed with CMD having undergone continuous thermodilution, compared to 36% by bolus. Mean coronary flow reserve was found to be significantly lower with continuous (2.62, SD 0.89) vs bolus (4.01, SD 2.51) thermodilution (p<0.0001). Of those positive for CMD, 28 patients had functional and 30 patients had structural CMD.An ANOCA endotype was identified in 66% of patients undergoing CFT. 2 or more ANOCA endotypes were identified in 11%. 43/128 patients had no ANOCA mechanism confirmed and 30% were adjudicated as non-cardiac chest pain.CCS class after CFT guided medication changes improved (67% of CCS 3-4 at baseline compared to 38% at 360 days).Conclusion In patients with R-ANOCA, abnormalities of invasive CFT are common. Treatment stratified by CFT results improved angina status and identifies patients who can be reassured from a coronary perspective and should be investigated for non-coronary symptom aetiologies. Invasive CFT should be considered in the work-up of patients with R-ANOCA.