Layer-specific circumferential strain using fast strain-encoded cardiac magnetic resonance imaging in acute myocardial injury - a prospective study of diagnostic and prognostic accuracy

Abstract

Abstract Background In patients presenting acutely with chest pain or shortness of breath, an acute myocardial injury diagnosed through modern troponin assays is common. Yet, a differential diagnosis is often demanding and must weigh the timely treatment of an ischemic cause against the risk of an invasive procedure without intervention. Modern cardiac magnetic resonance (CMR) strain sequences such as fast-SENC (fSENC) might support clinical decision-making in identifying predictors of myocardial dysfunction (1). Furthermore, their resolution should be able to differentiate epicardial from endocardial function impairment. This study sought to assess a layer-specific strain approach's diagnostic and prognostic accuracy using circumferential strain. Methods In this board-approved prospective observational study, patients from the emergency department fulfilling rule-in criteria for NSTEMI according to current guidelines received an ultra-fast fSENC CMR independently of standard care (2,3). fSENC was acquired in a single heartbeat acquisition, and global/segmental circumferential strain (GCS) as well as dysfunctional segments were measured. GCS was measured in two layers (epicardial/endocardial = GCSepi/GCSendo). Patients were followed up for two years for the occurrence of cardiovascular death and divided into groups according to their final diagnosis upon discharge. Results 64 patients (51 male) were included, consisting of 25 with NSTEMI, 16 with myocarditis and 23 with other causes of myocardial injury (OMI). GCS was reduced in all patients but with no significant difference between groups (NSTEMI: -14.3±3.8; myocarditis: 15.9±4.6; OMI: 13.9±3.8; p>0.05). GCSendo (-16.3±4.0) was generally lower than GCSepi (-12.5±3.1) in all groups (p < 0.001), but did not differ between groups (p>0.05). Overall, 2-year mortality was low (4.7%). Nevertheless, GCSendo predicted outcome (p = 0.03), unlike GCS. 2-year survival in patients with normal GCS (>-17%) and ≤5 dysfunctional segments was 100.0%. Conclusions Layer-specific circumferential strain is a significant predictor of prognosis. Endo- and epicardial strain is reduced in all types of myocardial injury. For the identification of underlying pathology however, layer-specific circumferential strain did not add incremental value.