Infarct Zone Circumferential Strain Independently Predicts Left Ventricular Functional Recovery After ST-Segment Elevation Myocardial Infarction: A Multiparametric CMR Study.

Background/

Objectives

Cardiac magnetic resonance (CMR) imaging provides a comprehensive assessment of myocardial injury after ST-segment elevation myocardial infarction (STEMI), yet the relative prognostic value of segmental infarct zone parameters compared with global indices for predicting left ventricular (LV) functional recovery remains incompletely defined. This study aimed to determine whether segmental infarct zone functional and structural CMR parameters provide prognostic information for LV functional recovery after a first STEMI treated with primary percutaneous coronary intervention (PCI).

Methods

In this prospective single-center study, 93 patients with a first STEMI (median age 61 years; 77% male) underwent CMR at baseline (median 3 days post-PCI) and at a 6-month follow-up. The comprehensive CMR assessment included cine imaging for volumetric and feature-tracking strain analysis, T1 and T2 mapping, and late gadolinium enhancement (LGE) for infarct size (IS) and microvascular obstruction (MVO) quantification. The myocardial segments were classified as infarcted, adjacent, or remote based on the LGE distribution. The primary outcome was unfavorable LV functional recovery, defined as failure to achieve an absolute increase of >10 percentage points in the LV ejection fraction (LVEF) or a follow-up LVEF ≤ 50%.

Results

At the 6-month follow-up, significant reverse remodeling was observed: the LVEF improved from 49.0% [40.7-52.4] to 55.8% [47.9-59.9] (p < 0.001), the LV end-systolic volume decreased from 91.8 mL [75.1-113.8] to 80.8 mL [61.9-108.3] (p = 0.005), and the relative IS decreased from 30.9% [18.9-45.5] to 19.0% [11.1-31.3] of LV mass (p < 0.001). At the follow-up, MVO was no longer detectable in any patient. Unfavorable functional recovery occurred in 17 patients (18.3%). In the multivariable analysis, the infarct zone circumferential strain (CS) was the strongest independent predictor of unfavorable recovery (OR 8.81; 95% CI 1.98-39.28; p = 0.004), followed by the relative IS (OR 4.02; 95% CI 1.03-15.73; p = 0.045) and a lower infarct zone post-contrast T1 (OR 4.40; 95% CI 1.12-17.36; p = 0.034).

Conclusions

Segmental infarct zone characteristics-particularly circumferential strain, post-contrast T1, and infarct size-provide clinically relevant prognostic information for LV functional recovery after STEMI. The infarct zone CS offers incremental predictive value beyond its structural parameters, reflecting the residual contractile reserve and myocardial viability.