Prognostic impact of inflammation in myocardial infarction with non-obstructive coronary arteries
Authors: Monteiro E , Barbosa J , Guimaraes J , Fernandes D , Costa G , Gomes R , Rosa J , Campos G , Baptista R , Monteiro P , Monteiro S , Goncalves F , Alves P , Goncalves L 
Published: November 2023

Abstract

Background
The prognosis of patients with myocardial infarction with non-obstructive coronary arteries (MINOCA) is worse than that of the general population. Nevertheless, the predictors for a worse outcome in patients with MINOCA are not fully determined.

Purpose
The aim of this study was to evaluate the prognostic value of C-Reactive Protein (CRP) in MINOCA patients.

Methods
Retrospective analysis of 706 consecutively admitted patients due to acute myocardial infarction (AMI), in whom coronary angiography revealed absence of obstructive coronary artery disease (≥50% stenosis). CRP levels were measured at admission. Demographic characteristics, symptoms at presentation, past medical history, laboratory characteristics and medication at discharge were examined. The primary endpoint analysed was all-cause mortality at 5 years. Possible predictors of the endpoint were assessed by Cox regression models. When statistically significant values were found in univariable analysis, multivariate analysis was used to determine whether CRP was an independent predictor of the outcome.

Results
In the studied sample, 55% of the patients were male. Median age was 64 [interquartile range (IQR) 55–72] and median body mass index was 27.3 kg/m2 (IQR 24.6-30.1). Regarding past medical history, 76.5% were hypertensive, 77.8% were dyslipidemic, 12.6% were smokers, 37.4% were diabetic and 59.3% had a previous history of angina. At presentation, 94.8% were in Killip 1, 3.8% were in Killip 2, 1% were in Killip 3 and 0.4% were in Killip 4. At admission, median CRP was 0.38 mg/dL (IQR 0.14-0.81), median Troponin I was 0.09 ng/ml (IQR 0.04-1.65), median creatinine was 0.85 mg/dL (IQR 0.73-1), median low density lipoprotein cholesterol (LDL-C) was 121.5 mg/dL (IQR 97.5-146), median haemoglobin was 13.6 g/dL (IQR 12.5-14.6) and median left ventricular ejection fraction (LVEF) was 58% (IQR 50-60). At discharge, 74.2% had a beta-blocker prescribed, 88.4% had a renin-angiotensin system inhibitor (RASi) prescribed, 98.2% had a statin prescribed and 76.5% had aspirin prescribed. All-cause mortality at 5 years was 8.5%. In univariable analysis, CRP was significantly associated with the endpoint [hazard ratio (HR) 1.138 per 1 mg/dL increase, 95% CI 1.090–1.188, p&lt;0.001], as was age, diabetes, Killip class, troponin I, creatinine, LDL-C, haemoglobin, LVEF and absence of prescription of RASi. In multivariate analysis, CRP remained significantly associated with the endpoint (HR 1.141, 95% CI 1.087–1.199, p&lt;0.001), as did age, creatinine and absence of prescription of RASi.

Conclusions
CRP at admission seems to be an independent predictor of all-cause mortality at the 5-year mark. This could indicate that inflammation has an important role in the pathophysiology and prognosis of MINOCA patients. It would be interesting to investigate if targeting inflammation would improve the long-term prognosis of these patients.