Clinical impact of coronary artery spasm in patients with no significant coronary stenosis who are experiencing acute coronary syndrome.

Background And Objective: To clarify the clinical features of coronary artery spasm (CAS) with no significant coronary stenosis in patients with suspected acute coronary syndrome (ACS) in real practice.

Methods: This is a retrospective observational study of patients with suspected ACS (n=645) based on symptoms, electrocardiographic changes, and/or positive cardiac biomarkers and vasospastic angina (VSA, n=90). ACS patients were divided into two groups: (1) organic ACS (n=515), culprit lesion ≥75% coronary stenosis with/without thrombosis; (2) spastic ACS (n=70), coronary stenosis <75%, either with positive acetylcholine (ACh) test (n=51) or without ACh test but verified spontaneous spasm (n=19). The study compared clinical characteristics among organic ACS, spastic ACS, and VSA.

Results: One hundred and thirty suspected ACS patients had a coronary organic stenosis <75% (130/645, 20%). Seventy of those patients (70/130, 54%) were confirmed to have CAS, and these accounted for 11% of all ACS patients (70/645). The rate of cigarette smoking was highest in the spastic ACS. No spastic ACS patients died during their hospital stay or after discharge, whereas acute myocardial infarction occurred in 19%, aborted sudden cardiac death in 6%, multivessel spasm was provoked in 78%, and diffuse spasm was more frequently provoked than in the VSA group (82% vs. 62%).

Conclusions: CAS is not a rare cause of ACS. Although the prognosis of spastic ACS is good, there are occasional critical cases. An initial differential diagnosis including an ACh test is thus important to decide the treatment strategy of ACS.