Exploring the impact of coronary microvascular dysfunction on cardiac remodeling after st-elevation myocardial infarction
Authors: Aldujeli A , Tsai T , Haq A , Grabauskyte I , Tatarunas V , Briedis K , Unikas R , Onuma Y , Brilakis E , Serruys P W 
Published: October 2024

Abstract

Background
The complex interplay between Coronary Microvascular Dysfunction (CMD) and ST-segment Elevation Myocardial Infarction (STEMI) presents significant clinical hurdles. CMD, commonly seen as a complication following STEMI, is associated with adverse cardiovascular outcomes and persistent anginal symptoms. Despite its clinical relevance, the link between CMD post-STEMI and subsequent left ventricular (LV) diastolic dysfunction, along with functional LV remodelling (FLVR), is yet to be fully explored.

Purpose
Examine the link between CMD 3 months post-STEMI and its impact on FLVR and diastolic dysfunction.

Methods
This prospective, observational cohort study focused on STEMI patients. At 3-month post-STEMI, a comprehensive coronary physiology assessment of the culprit artery was conducted using the thermodilution method to measure fractional flow reserve (FFR), coronary flow reserve (CFR), and the index of microcirculatory resistance (IMR). CMD was identified with an IMR ≥ 25 or a CFR &lt; 2.0, assuming an FFR &gt; 0.80.
Diastolic dysfunction was classified according to ASE/EACVI 2016 guidelines. FLVR was categorized as per Surenjav Chimed et al.'s criteria: Group I with no significant changes in LV size or function, Group II with a decrease in LV ejection fraction (LVEF) greater than 5% without LV dilatation, Group III with an increase in left ventricular end-diastolic volume (LVEDV) ≥ 20%, and Group IV showing both an increase in LVEDV ≥ 20% and a decrease in LVEF over 5%. The study aimed to elucidate the relationship between CMD and the progression of FLVR and diastolic dysfunction, tracked over a 12-month period.

Results
The study involved 210 patients, mostly men (59.5%), with a median age of 65 (IQR: 58–76). At the 3-month follow-up, CMD was observed in 57 (27.1%) patients. CMD patients had a higher female prevalence (63.2% vs. 32.0%; p &lt; 0.001) and more diabetes (42.1% vs. 17.7%; p &lt; 0.001) compared to non-CMD patients. Both groups shared similar body mass indices, medications, and other risk factors. Laboratory results were similar between groups, except brain natriuretic peptide levels were higher in CMD patients (70.0 vs. 37.0 ng/L; p &lt; 0.001). After 12 months, CMD patients demonstrated significantly less recovery in LVEF (-10.00% vs. 8.00%; p &lt; 0.001), higher prevalence of grade 2 LV diastolic dysfunction (73.08% vs. 1.32%; p &lt; 0.001), and a higher incidence of advanced FLVR (notably in Groups 3 and 4) compared to non-CMD (11.32% vs. 7.28% and 22.64% vs. 1.99%, respectively; p &lt; 0.001). In the adjusted multivariable logistic regression analysis, IMR values independently predicted more severe FLVR and diastolic dysfunction.

Conclusions
This study highlights that CMD 3 months after STEMI is linked to worse FLVR, diastolic dysfunction, and less recovery in LVEF, emphasizing the need for early CMD detection for better risk assessment. Further research is essential to explore underlying mechanisms and intervention opportunities.LVEF Changes at 12 Months by CMD StatusDiastolic Dysfunction and LV Remodeling