Inflammatory and imaging predictors of development of ischemic mitral regurgitation following ST-elevation myocardial infarction
Authors: Valeur A , Dregoesc I , Grymyr L M D , Berg-Hansen C E , Bleie Ø , Steigen T , Manole S , Larsen T , Urheim S , Iancu A , Cramariuc D 
Published: January 2025

Abstract

Background
Development of ischemic mitral regurgitation (MR) after ST-elevation acute myocardial infarction (STEMI) is a complex process that is less understood mechanistically, challenging to assess by standard echocardiography and associated with worse cardiovascular outcomes.

Purpose
To identify predictors of post-STEMI MR through serial assessment of biomarkers of inflammation and myocardial injury, and cardiac remodeling by echocardiography and cardiac magnetic resonance (CMR).

Methods
In the Registry for Post-myocardial Infarction Left Ventricular Remodeling and Heart Failure Prevention (REDEFINE-HF), 94 patients with STEMI (60±10 years, 76% men) were investigated in the acute infarction phase and at 6-month follow-up by both bio- and imaging markers. Left ventricular (LV) end-diastolic (EDV) and end-systolic (ESV) volumes were assessed by both echocardiography and CMR. MR ẃas graded by a multiparametric echo-approach as by current guidelines. LV filling pressures were estimated from the mitral peak early diastolic flow to annulus velocity ratio (E/e´). Additionally, the extent of microvascular obstruction and intramyocardial hemorrhage (an index of reperfusion injury) were assessed by CMR at baseline. The primary outcome was a composite of death, heart failure hospitalizations, and acute myocardial infarction during follow-up.

Results
In acute STEMI phase, 57% of patients had mild and 13% moderate MR, with an increase in prevalence to 79% mild and 15% moderate MR at 6-month follow-up (p&lt;0.001). Patients with both acute-phase and 6-month follow-up MR had higher baseline troponin T and interleukin-6, higher concomitant LV filling pressures and echo-ESV, and larger infarction size by CMR (all p&lt;0.05). In logistic regression analysis, mild-moderate acute-phase MR was associated with higher LV CMR-ESV after adjustment for clinical, biochemical and imaging confounders (p&lt;0.05, R2=0.42). In Cox regression analysis, mild-moderate 6-month post-STEMI MR was predicted by higher baseline interleukin-6 (HR 1.01 [1.00-1.03] and more extensive acute-phase intramyocardial hemorrhage (HR 1.20 [1.03-1.40]) and microvascular obstruction by CMR (HR 1.14 [1.03-1.23]) (all p&lt;0.05), but not by comorbidities, daily medication, total ischemic time, culprit vessel or extent of coronary artery disease. During 19±8months follow-up, 17 events occurred, all in patients with ischemic MR at follow-up (bootstrap p&lt;0.001). Higher age and larger LV CMR-ESV were independent predictors of the composite outcome (-2Log likelihood 50, both p&lt;0.05).

Conclusion
Ischemic mild-moderate MR occurs through complex interactions between inflammatory, microvascular and tissue remodeling pathways. A multimodality approach combining bio- and imaging markers helps identify individuals at risk for this clinical condition pertaining negative prognostic implications.