C-reactive protein: Marker of poor prognosis in ST-elevation myocardial infarction (STEMI) patients?
Authors: Grech N , Mizzi J M , Cuschieri A , Cassar Maempel A 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Introduction
Recent evidence suggests that C-reactive peptide (CRP) may play an important role as a marker of unstable atheromatous plaque and acute coronary syndrome (ACS). A recent retrospective study involving 102,337 ACS patients found that CRP elevation resulted in a significant increase in short- and long- term mortality. This association may present an opportunity to improve patient selection for therapeutics such as immunomodulatory drugs targeting inflammation and hence, reducing cardiovascular events.

Purpose
To determine the prognostic value of CRP in patients presenting with an ST-elevation myocardial infarction (STEMI).

Methods
All patients which presented with a STEMI in 2016 and 2017 were included in this retrospective, observational study. Exclusion criteria included patients who did not have a CRP taken at point of contact to hospital prior to PPCI, patients who were treated conservatively (no PPCI), and patients who have any condition which may increase CRP levels regardless to STEMI (active inflammatory disease, infective process, or malignancy). All data was collected from online hospital systems.
Prognosis was evaluated based on major adverse cardiovascular events (unstable angina requiring hospitalisation, myocardial infarction [MI], hospitalisation due to pulmonary oedema and revascularization with repeat PCI or coronary artery bypass [CABG]) and all-cause mortality. Patients were followed up till September 2022, maintaining a minimum of a 5-year follow up. Patients were stratified into 3 groups according to CRP levels; Group 1: 0-5mg/L (normal), Group 2: 5-15mg/L and Group 3: ≥15mg/L. Chi-square was used for statistical analysis of categorical data. Kruskal–Wallis 1-way analysis of variance test was used for continuous data after finding a non-normal distribution. P value &lt;0.05 was considered significant.

Results
438 patients presented with a STEMI to our hospital in 2016 and 2017. A total of 185 patients were excluded as no CRP was available. A further 13 patients were excluded as they were noted to have an ongoing infective process, malignancy, or inflammatory condition. 2 patients were excluded as they did not undergo PPCI. The remaining study cohort included 238 patients distributed as per Figure 1. Baseline characteristics were collected; no statistically significant differences were noted (Figure 1). Statistically more MACEs and all-cause deaths were noted in groups with higher CRP levels (apart from CABG) (Figure 1).
Kaplan-Meier curves for time-to-first MACE and cumulative survival indicated a statistically significant poorer outcome in patients with higher CRP levels (p&lt;0.0001 and p=0.0004, respectively) (Figure 2).

Conclusion
Higher CRP levels taken prior to PPCI has been shown to be related with a poorer prognosis in patients presenting with STEMI. Further prospective work is required to explore the inflammation pathway in ischaemic heart disease patients.