Post-occlusive reactive hyperaemia can objectify the occurrence of vasospasm induced ischemia during acetylcholine provocation testing

Abstract

Abstract Introduction Acetylcholine (ACh) spasm provocation testing together with the diagnostic criteria published by the Coronary Vasomotor Disorders International Study Group (COVADIS) are considered the gold standard for the diagnosis of coronary vasospasm in contemporary clinical practice. In 20–29% of patients undergoing vasospasm provocation an equivocal test result occurs when these criteria are only partially met and poses a diagnostic dilemma. Post-occlusive reactive hyperaemia is a marker of acute myocardial ischemia and could serve as an added objective diagnostic criterium for the diagnosis of acetylcholine induced vasospasm. Purpose The aim of this study is therefore to evaluate the occurrence of post-occlusive reactive hyperaemia in the equivocal, positive and negative test result that follows acetylcholine vasospasm provocation. Methods 66 patients with angina and non-obstructive coronary artery disease on angiography (ANOCA) who underwent the entire ACh spasm provocation testing protocol were included in this analysis. After each ACh dose angiography was performed and when vasospasm occurred 200 μg nitro-glycerine was administered intracoronary. Definitions and diagnostic criteria for CAS were in line with those used by the COVADIS working group to diagnose epicardial and microvascular vasospasm. An equivocal test result was defined as the induction of recognisable angina without ischemic ECG changes, in reaction to ACh. Doppler flow was continuously measured during the procedure. Changes in flow due to ACh mediated vasodilation quickly return to baseline values due to its short-half life. Therefore, the occurrence of post-ischemic reactive hyperaemia was assessed by the extended time to return to baseline flow, the so called “flow recovery time”. Results We analysed the flow recovery time in 21 patients with epicardial vasospasm, in 16 with microvascular spasm, in 14 with an equivocal test result and in 15 with a negative test result. Mean age of the entire study population was 56±11 years and 86% were female. In reaction to dose 1 to 3 flow recovery time was similar between all diagnostic endotypes. In reaction to the fourth dose flow recovery time was extended in the epicardial, microvascular and equivocal test result compared to the negative test result indicative of post-ischemic reactive hyperaemia. Conclusion Post-occlusive reactive hyperaemia occurs in patients with an equivocal test result similar to patients with microvascular vasospasm and epicardial vasospasm. These findings indicate the occurrence of acetylcholine induced vasospasm in the equivocal test result and these patients may benefit from medical treatment. Funding Acknowledgement Type of funding sources: None.