Segmental Strain for Scar Detection in Acute Myocardial Infarcts and in Follow-up Exams using Non-Contrast CMR Cine Sequences

Abstract

Background The purpose of the study was to investigate feasibility of infarct detection in segmental strain derived from non-contrast cardiac magnetic resonance (CMR) cine sequences in patients with acute myocardial infarction (AMI) and in follow-up (FU) exams.Methods57 patients with AMI (mean age 61 ± 12 years, CMR 2.8 ± 2 days after infarction) were retrospectively included, FU exams were available in 32 patients (35 ± 14 days after first CMR). 28 patients with normal CMR (47 ± 8 years) served as controls. Dedicated software (Segment CMR, Medviso) was used to calculate global and segmental strain derived from cine sequences. Cine short axis stacks and segmental circumferential strain calculations of every patient and control were presented to two blinded readers in random order, who were advised to identify potentially infarcted segments, blinded to LGE and clinical information. Results Impaired global strain was measured in AMI patients compared to controls (global peak circumferential strain [GPCS] p= 0.01; global peak longitudinal strain [GPLS] p= 0.04; global peak radial strain [GPRS] p= 0.01). In both imaging time points, mean segmental peak circumferential strain [SPCS] was impaired in infarcted tissue compared to remote segments (AMI: p=0.03, FU: p=0.02). SPCS values in infarcted segments were similar between AMI and FU (p=0.8), remote segments were marginally more impaired in AMI than in FU (p= 0.07). In SPCS calculations, 141 from 189 acutely infarcted segments were accurately detected (74.6%), visual evaluation of correlating cine images detected 44.4% infarcts. In FU, 81.5 % infarcted segments (93/114 segments) were detected in SPCS and 51.8% by visual evaluation of correlating short axis cine images (p=0.01).ConclusionSegmental circumferential strain derived from routinely acquired native cine sequences detects nearly 75 % of acute infarcts and about 80% of infarcts in subacute follow-up CMR, significantly more than visual evaluation of correlating cine images alone. Acute infarcts may display only subtle impairment of wall motion and no obvious wall thinning, thus SPCS calculation might be helpful for scar detection in patients with acute infarcts, when only cine images are available.