Functional and prognostic implications of cardiac magnetic resonance feature tracking-derived remote myocardial strain analyses in patients following acute myocardial infarction

Abstract

Background: Cardiac magnetic resonance myocardial feature tracking (CMR-FT)-derived global strain assessments provide incremental prognostic information in patients following acute myocardial infarction (AMI). Functional analyses of the remote myocardium (RM) are scarce and whether they provide an additional prognostic value in these patients is unknown.

Methods: 1034 patients following acute myocardial infarction were included. CMR imaging and strain analyses as well as infarct size quantification were performed after reperfusion by primary percutaneous coronary intervention. The occurrence of major adverse cardiac events (MACE) within 12 months after the index event was defined as primary clinical endpoint.

Results: Patients with MACE had significantly lower RM circumferential strain (CS) compared to those without MACE. A cutoff value for RM CS of - 25.8% best identified high-risk patients (p < 0.001 on log-rank testing) and impaired RM CS was a strong predictor of MACE (HR 1.05, 95% CI 1.07-1.14, p = 0.003). RM CS provided further risk stratification among patients considered at risk according to established CMR parameters for (1) patients with reduced left ventricular ejection fraction (LVEF) ≤ 35% (p = 0.038 on log-rank testing), (2) patients with reduced global circumferential strain (GCS) > - 18.3% (p = 0.015 on log-rank testing), and (3) patients with large microvascular obstruction ≥ 1.46% (p = 0.002 on log-rank testing).

Conclusion: CMR-FT-derived RM CS is a useful parameter to characterize the response of the remote myocardium and allows improved stratification following AMI beyond commonly used parameters, especially of high-risk patients.

Trial registration: ClinicalTrials.gov, NCT00712101 and NCT01612312 Defining remote segments (R) in the presence of infarct areas (I) for the analysis of remote circumferential strain (CS). Remote CS was significantly lower in patients who suffered major adverse cardiac events (MACE) and a cutoff value for remote CS of - 25.8% best identified high-risk patients. In addition, impaired remote CS ≥ - 25.8 % (Remote -) and preserved remote CS < - 25.8 % (Remote +) enabled further risk stratification when added to established parameters like left ventricular ejection fraction (LVEF), global circumferential strain (GCS) or microvascular obstruction (MVO).

Keywords: CMR; Feature tracking; Myocardial infarction; Remote strain; Risk prediction.

Fig. 1

Definition of remote myocardium according to late gadolinium enhancement. Based on the AHA 16-segment model, myocardium was classified as infarcted (I) or remote (R) segments. After delineation of epi- (green) and endocardial borders (red), infarct area was plotted (red area within myocardium) and a bull’s eye displaying affected myocardial tissue (in %) was generated. The adjacent segments next to a RM segment within one layer and the adjacent segments of more basal or apical slices had to be unaffected by infarct area enhancement to define RM myocardium. S septal, L lateral

Fig. 2

Flowchart

Fig. 3

Correlation of remote CS with left ventricular (LV) ejection fraction and infarct size. Correlation of remote CS with left ventricular ejection fraction (left) and infarct size (right). CS global circumferential strain, % LV percent left ventricular mass

Fig. 4

Remote CS and survival after acute myocardial infarction. Incidence of MACE (major adverse cardiac events) according to high and low remote circumferential strain (CS)

Fig. 5

Remote circumferential strain (CS) and survival in subgroup analyses. Incidence of MACE (major adverse cardiac events) according to high and low remote circumferential strain (cutoff value − 25.8%) in subgroups of global circumferential strain (GCS), left ventricular ejection fraction (LVEF), infarct size (IS) and microvascular obstruction (MVO) dichotomized to high- and low-risk cohorts using optimal cutoff points