STEMI with mid-range ejection fraction: a group of intermediate risk not to be forgotten
Authors: Ferreira J , Fonseca M , Goncalves S , Farinha J.M , Esteves A.F , Pinheiro A , Coelho R , Costa C , Caria R 
Published: October 2021

Abstract

Background
Reduced left ventricular ejection fraction (LVEF) &lt;40% is an important negative prognostic factor in the setting of ST-elevation acute myocardial infarction (STEMI). On the other hand, data concerning mid-range LVEF (mrEF) post-STEMI are scarce. Consequently, recommendations regarding reassessment of LVEF or administration of neurohormonal medication in this group of patients (pts) are also lacking.

Purpose
To assess the current treatment and prognosis of STEMI with mrEF.

Methods
Retrospective study including all consecutive pts hospitalized for STEMI and submitted to primary percutaneous coronary intervention in a Cardiology centre in 2018. Pts were divided into 3 groups according to LVEF assessed before hospital discharge: preserved EF (pEF: LVEF ≥50%), mid-range EF (mrEF: LVEF 40–49%) and reduced EF (rEF: LVEF &lt;40%). We analysed clinical characteristics, treatment, evolution of LVEF post-STEMI and clinical outcomes - death, myocardial infarction (MI) and hospitalization for heart failure (HF) – of the mrEF group and compared it with pEF.

Results
188 pts with a mean age of 61 years were admitted for STEMI in 2018. The majority (58%, n=109) had pEF; 29% (n=55) had mrEF and 13% (n=24) were in the rEF group. Pts in the mrEF group had similar baseline characteristics to the others. However, compared with pEF, culprit-lesion was more often located in left main or left anterior descending arteries (80% vs 35%, p&lt;0.001) and NT-proBNP levels were higher in mrEF pts (2270 vs 881 pg/mL, p&lt;0.001).
At discharge, all mrEF patients were medicated with a renin-angiotensin-aldosterone blocker and 91% with a beta-blocker.
After a median of 8 months, LVEF improved a mean of 4% (± 9%) in the mrEF group. However, in 12.5% LVEF worsened to &lt;40% (vs 0 in the pEF group, p=0.006).
At a median follow-up of 2.6 years, there was an increase in mortality according to the EF group (pEF 4% vs mrEF 13% vs rEF 48%, log-rank: p&lt;0.001 – fig. 1) with a hazard ratio (adjusted for age) of 3.75 (95% CI 1.1–12.8, p=0.035) for mrEF vs pEF. There was also a non-significant tendency to higher rates of the composite endpoint of MI and hospitalization for HF in the mrEF group vs pEF (8.2% vs 2.9%, p=0.213).

Conclusions
This study confirms previous reports of the worse prognosis of STEMI with mrEF and suggests the existence of a continuum of risk of adverse clinical outcomes according to LVEF. Therefore, this group of intermediate risk might also benefit from neurohormonal medication, which is only specifically recommended for rEF in current STEMI guidelines. It also highlights the importance of a closer follow-up (with reassessment of LVEF) of mrEF pts since a non negligeable proportion ultimately progress to rEF and may require additional medical treatment or even an implantable cardioverter defibrillator. Further research with larger samples is required to identify predictors of worsening LVEF and assess the impact of neurohormonal modulation in this population.

Funding Acknowledgement
Type of funding sources: None. Kaplan-Meier Survival Analysis