Predictors of segmental myocardial functional recovery in patients after an acute ST-Elevation myocardial infarction

Abstract

Objective: We hypothesized that Displacement Encoding with Stimulated Echoes (DENSE) and feature-tracking derived circumferential strain would provide incremental prognostic value over the extent of infarction for recovery of segmental myocardial function.

Methods: Two hundred and sixty-one patients (mean age 59 years, 73% male) underwent MRI 2 days post-ST elevation myocardial infarction (STEMI) and 241 (92%) underwent repeat imaging 6 months later. The MRI protocol included cine, 2D-cine DENSE, T2 mapping and late enhancement. Wall motion scoring was assessed by 2-blinded observers and adjudicated by a third. (WMS: 1=normal, 2=hypokinetic, 3=akinetic, 4=dyskinetic). WMS improvement was defined as a decrease in WMS ≥ 1, and normalization where WMS = 1 on follow-up. Segmental circumferential strain was derived utilizing DENSE and feature-tracking. A generalized linear mixed model with random effect of subject was constructed and used to account for repeated sampling when investigating predictors of segmental myocardial improvement or normalization RESULTS: At baseline and follow-up, 1416 segments had evaluable data for all parameters. Circumferential strain by DENSE (p < 0.001) and feature-tracking (p < 0.001), extent of oedema (p < 0.001), infarct size (p < 0.001), and microvascular obstruction (p < 0.001) were associates of both improvement and normalization of WMS. Circumferential strain provided incremental predictive value even after accounting for infarct size, extent of oedema and microvascular obstruction, for segmental improvement (DENSE: odds ratio, 95% confidence intervals: 1.08 per -1% peak strain, 1.05-1.12, p < 0.001, feature-tracking: odds ratio, 95% confidence intervals: 1.05 per -1% peak strain, 1.03-1.07, p < 0.001) and segmental normalization (DENSE: 1.08 per -1% peak strain, 1.04-1.12, p < 0.001, feature-tracking: 1.06 per -1% peak strain, 1.04-1.08, p < 0.001).

Conclusions: Circumferential strain provides incremental prognostic value over segmental infarct size in patients post STEMI for predicting segmental improvement or normalization by wall-motion scoring.

Keywords: DENSE; Displacement encoding with stimulated echoes; Myocardial strain; STEMI.

Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.

Figures

Fig. 1

Study flow diagram.

Fig. 2

Infarct pathology and its prediction of segmental myocardial function. A 58 year old male presented with an anterior ST-elevation myocardial infarction, and had angioplasty to his left anterior descending coronary artery. He underwent an MRI scan on day 3 of his admission, and at 6 months follow-up. All the images are co-located, short-axis, mid-left ventricular images. Top row, shows cine imaging in diastole and systole. The anterior, antero-septal and infero-septal segments were scored as being akinetic by 2 independent observers. Middle row, left to right, demonstrates a T2 parametric map with a higher values (grey-yellow) signifying oedema in the region of the infarct. The middle figure is a DENSE peak end-systolic strain map, which illustrates the remote zone in blue and the infarcted region as yellow and green. The next image is late-gadolinium enhancement image, depicting a hyperintense infarcted region with some microvascular obstruction. At 6-month follow-up, (bottom row), the antero-septal region is still akinetic and thinned. The strain in the akinetic regions was under the cut-off (−8.17%) identified for segmental improvement. Strain map generated by Dr D.A. Auger through post-processing.

Fig. 3

Oedema and infarct size divided according to wall-motion scoring at baseline. Segmental oedema (area-at-risk, green) and baseline infarct size (grey) increased as wall-motion scoring increased. A score of 4 was associated with a larger segmental infarct size and oedema.