Acute Coronary Syndrome With Nonobstructive Coronary Arteries: The Severity of Coronary Atherosclerosis and Myocardial Perfusion Disorders (Pilot Study)

Abstract

Aim. To study the structural and functional status of coronary blood flow in patients with acute coronary syndrome with nonobstructive coronary arteries using multispiral computed tomography (MSCT) and single photon emission tomography (SPECT) and to compare data of MSCT and invasive coronary angiography (ICA).Material and Methods. This study is a non-randomized, open-label, controlled clinical trial. The study is registered on ClinicalTrials.gov. The inclusion criteria are listed on the site. All patients underwent CT and SPECT.Results. The study included 14 patients with MINOCA; the group comprised predominantly women (n=11, 78.6%); the average age was 61.1±14 years. The risk according to GRACE (Global Registry of Acute Coronary Events) risk score was moderate in 8 patients (57%) and high in 5 patients (35.7%). 85.7% of patients were admitted to hospital within the first six hours from onset of diseases. Three patients (21.4%) received thrombolytic therapy and it was effective in two of them (14%). Risk factors included hypertension (64.2%), dyslipidemia (50%), and burdened history (71.4). According to the results of invasive coronary angiography, intact coronary arteries were detected in 9 patients (64.3%); 5 patients (35.7%) had stenosis up to 50%. Coronary slow-flow phenomenon (TIMI 2) was detected in 11 patients (78.6%) including 8 patients (57.1%) who had coronary slow-flow phenomenon and intact coronary arteries. Severe coronary spasm was registered in 1 patient (7.1%) in the group with ST segment elevation acute coronary syndrome (STE ACS). According to MSCT data, the proportion of patients with intact coronary arteries decreased from 7 (50%) to 5 patients (35.7%) whereas the proportion of patients with nonstenosing atherosclerosis increased from 7 (50%) to 9 patients (64.3%). Twenty six atherosclerotic plaques were detected including eccentric (76%), circular (11.5%), and semi-circular plaques (11.5%). In regard to morphological structure, the atherosclerotic plaques were calcified (59.5%), mostly calcified (7.7%), and soft (29%). Normal myocardial perfusion (Summed Stress Score (SSS) and Summed Rest Score (SRS) <4) was detected in two patients (14.3%); 12 patients (85%) had transitory perfusion defects. The median score values were 7.5 (4; 13) for SSS, 4.7 (1.0; 9.0) for SRS, and 4.7 (3.0; 8.0) for SDS.Conclusion. The introduction of MCTA and SPECT into the algorithm of the examination of patients with acute myocardial infarction and non-obstructive atherosclerosis of the coronary arteries was safe when additionally used during index hospitalization. These approaches provided new information about the structure and function of the coronary arteries. These data provide rationale for further study using a larger group of patients to determine a prognostic significance of detecting the atherosclerotic plaques with the signs of instability in this patient category.