Background: The high accuracy of feature-tracking cardiac magnetic resonance (CMR) imaging qualifies this novel modality as potential gold standard for myocardial strain analyses in ST-elevation myocardial infarction patients; however, the incremental prognostic validity of feature-tracking-CMR over left ventricular ejection fraction (LVEF) and myocardial damage remains unclear. This study therefore aimed to determine the value of myocardial strain measured by feature-tracking-CMR for the prediction of clinical outcome following ST-elevation myocardial infarction.
Methods: This prospective observational study enrolled 451 revascularized ST-elevation myocardial infarction patients. Comprehensive CMR investigations were performed 3 (interquartile range, 2-4) days after infarction to determine LVEF, global longitudinal strain (GLS), global radial strain, and global circumferential strain as well as myocardial damage. Primary end point was a composite of death, re-infarction, and congestive heart failure (major adverse cardiac events [MACE]).
Results: During a follow-up of 24 (interquartile range, 11-48) months, 46 patients (10%) experienced a MACE event. All 3 strain indices were impaired in patients with MACE (all P<0.001). However, GLS emerged as the strongest MACE prognosticator among strain parameters (area under the curve, 0.73 [95% CI, 0.69-0.77]) and was significantly better (P=0.005) than LVEF (area under the curve, 0.64 [95% CI, 0.59-0.68]). The association between GLS and MACE remained significant (P<0.001) after adjustment for global radial strain, global circumferential strain, and LVEF as well as for infarct size and microvascular obstruction. The addition of GLS to a risk model comprising LVEF, infarct size, and microvascular obstruction led to a net reclassification improvement (0.35 [95% CI, 0.14-0.55]; P<0.001).
Conclusions: GLS by feature-tracking-CMR strongly and independently predicted the occurrence of medium-term MACE in contemporary revascularized ST-elevation myocardial infarction patients. Importantly, the prognostic value of GLS was superior and incremental to LVEF and CMR markers of infarct severity.
Keywords: ST-segment elevation myocardial infarction; magnetic resonance imaging; myocardial strain.