Left ventricular functional recovery of infarcted and remote myocardium after ST-segment elevation myocardial infarction (METOCARD-CNIC randomized clinical trial substudy)

Abstract

Background: We aimed to evaluate the effect of early intravenous metoprolol treatment, microvascular obstruction (MVO), intramyocardial hemorrhage (IMH) and adverse left ventricular (LV) remodeling on the evolution of infarct and remote zone circumferential strain after acute anterior ST-segment elevation myocardial infarction (STEMI) with feature-tracking cardiovascular magnetic resonance (CMR).

Methods: A total of 191 patients with acute anterior STEMI enrolled in the METOCARD-CNIC randomized clinical trial were evaluated. LV infarct zone and remote zone circumferential strain were measured with feature-tracking CMR at 1 week and 6 months after STEMI.

Results: In the overall population, the infarct zone circumferential strain significantly improved from 1 week to 6 months after STEMI (- 8.6 ± 9.0% to - 14.5 ± 8.0%; P < 0.001), while no changes in the remote zone strain were observed (- 19.5 ± 5.9% to - 19.2 ± 3.9%; P = 0.466). Patients who received early intravenous metoprolol had significantly more preserved infarct zone circumferential strain compared to the controls at 1 week (P = 0.038) and at 6 months (P = 0.033) after STEMI, while no differences in remote zone strain were observed. The infarct zone circumferential strain was significantly impaired in patients with MVO and IMH compared to those without (P < 0.001 at 1 week and 6 months), however it improved between both time points regardless of the presence of MVO or IMH (P < 0.001). In patients who developed adverse LV remodeling (defined as ≥ 20% increase in LV end-diastolic volume) remote zone circumferential strain worsened between 1 week and 6 months after STEMI (P = 0.036), while in the absence of adverse LV remodeling no significant changes in remote zone strain were observed.

Conclusions: Regional LV circumferential strain with feature-tracking CMR allowed comprehensive evaluation of the sequelae of an acute STEMI treated with primary percutaneous coronary intervention and demonstrated long-lasting cardioprotective effects of early intravenous metoprolol.

Trial registration: ClinicalTrials.gov, NCT01311700. Registered 8 March 2011 - Retrospectively registered.

Keywords: Feature-tracking cardiovascular magnetic resonance; Intramyocardial hemorrhage; Intravenous metoprolol; Left ventricular remodeling; Microvascular obstruction; ST-segment elevation myocardial infarction.

Conflict of interest statement

JSG is a Philips Healthcare employee. CBD is a consultant for Circle Cardiovascular Imaging. VD and JJB received speaker fees from Abbott Vascular. The remaining authors have nothing to disclose.

Figures

Fig. 1

Definition of the infarct and remote zone myocardium. a, In case the culprit coronary artery lesion was in the proximal left anterior descending coronary artery (LAD), the infarct zone was defined according to the 16-segment model of the left ventricle (LV) with the segments 1–2, 7–8 and 13–16 and the rest of the LV myocardium was defined as the remote zone. b, If the culprit lesion was found in mid or distal LAD, the infarct zone included segments 7–8 and 13–16 and the rest of LV myocardium was defined as the remote zone. LAD, left anterior descending; LCX, left circumflex; LM, left main

Fig. 2

The infarct zone and the remote zone strain after ST-segment elevation myocardial infarction (STEMI) in patients receiving early intravenous metoprolol versus controls. Left ventricular (LV) infarct zone and remote zone strains are schematically presented with the mean values in patients receiving early intravenous metoprolol and in patients receiving conventional treatment at 1 week and at 6 months after STEMI. LV was split into the infarct and the remote zone as explained in Fig. 1. In order to schematically present different infarct territories in patients with proximal left anterior descending coronary artery (LAD) coronary artery infarcts and mid-distal LAD infarcts, fainter colors were used to paint the basal anterior and anteroseptal segments, signifying that these segments were either included in the infarct zone (proximal LAD infarcts) or remote zone (mid-distal LAD infarcts) strain analysis. Comparisons between 1-week and 6-month strains are graphically represented on the right-hand side using the same model, with corresponding P-values shown separately for the infarct and remote zone strain analysis. In addition, comparisons between the metoprolol and the control group are shown in the bottom row

Fig. 3

A patient with a proximal LAD infarct receiving standard STEMI treatment. a, balanced steady state free precession (bSSFP) end-diastolic images with endo- and epi-cardial contours. The patient developed adverse left ventricular (LV) remodeling (defined as ≥ 20% increase in LV end-diastolic volume (LVEDV) and had a slight reduction in LV ejection fraction (LVEF) at 6 months after STEMI. b, T2-weighted short tau inversion recovery (STIR) images, showing the presence of edema (white arrows) and intramyocardial hemorrhage (IMH) (yellow arrowheads) at 1-week after STEMI. c, late gadolinium enhancement (LGE) images, showing the presence of acute ischemic injury (white arrows) with microvascular obstruction (MVO, yellow arrowheads) at 1 week after STEMI and infarct scar (white arrows) at 6-months. d, end-systolic bSSFP images with feature-tracking circumferential LV strain overlay. At 6 months the infarct zone circumferential strain improved despite the presence of a huge infarct with IMH and MVO in the acute phase, while the remote zone strain slightly declined bSSFP, balanced steady state free precession; ED, end-diastolic; ES, end-systolic; IMH, intramyocardial hemorrhage; LAD, left anterior descending coronary artery, LGE, late gadolinium enhancement; LV, left ventricular; LVEDV, left ventricular end-diastolic volume; LVEF, left ventricular ejection fraction; MVO, microvascular obstruction; SSFP, steady-state free precession; STEMI, ST-segment elevation myocardial infarction; STIR, short tau inversion recovery.

Fig. 4

A patient with a mid-LAD infarct receiving early intravenous metoprolol. a, bSSFP end-diastolic images with endo- and epi-cardial contours. The LV volumes remained stable and the LVEF increased at 6 months after STEMI. b, T2-STIR images showing the presence of edema (white arrows) at 1-week after STEMI. c, LGE images showing the presence of acute ischemic injury/infarct scar (black arrows) at 1 week/6-months after STEMI. d, end-systolic bSSFP images with feature-tracking circumferential LV strain overlay. At 6 months the infarct zone circumferential strain improved while the remote zone strain remained stable The same abbreviations were used as in Fig. 3