Segmental Strain for Myocardial Scar Detection in Acute Infarcts and Follow-Up CMR Using Non-Contrast Cine Images

Aims Scar tissue from myocardial infarction is best visualized with cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE). Gadolinium-free alternatives for detection of myocardial scars are limited. This study investigated the feasibility of myocardial scar detection in acute infarcts and follow-up CMR using non-contrast cine images. Methods Fifty-seven patients with acute infarcts (15 female, mean age 61 ± 12 years, CMR 2.8 ± 2 days after infarction) were retrospectively evaluated with follow-up CMR exams available in thirty-two patients (9 female, 35 ± 14 days after infarction). Twenty-eight patients with normal CMR scans (2 female, mean age 47 ± 8 years) served as controls. Global and segmental strain parameters (global peak circumferential [GPCS], global peak longitudinal [GPLS], global peak radial strain [GPRS], segmental peak circumferential [SPCS], segmental peak longitudinal [SPLS], and segmental peak radial strain [SPRS]) were calculated from standard non-contrast balanced SSFP cine sequences using commercially available software (Segment CMR, Medviso, Sweden). Visual assessment of wall motion abnormalities on short axis cine images, as well as segmental circumferential strain calculations (endo-/epicardially contoured short axis cine and resulting polar plot strain map) of every patient (acute imaging and follow-up CMR) and control were presented for two blinded readers in random order, who were advised to localize potentially infarcted segments, blinded to LGE images and clinical information. Results While global strain values were impaired in patients with acute infarcts compared to controls (GPCS p= 0.01; GPLS p= 0.04; GPRS p= 0.01), global strain was similar between first CMR and follow-up imaging in the subgroup of 32 patients (GPCS p= 0.7; GPLS p=0.8; GPRS p=0.2). In acute infarcts and in follow-up CMR, patients had reduced mean SPCS in infarcted segments compared to remote myocardium (acute p= 0.03, follow-up exams p= 0.02). SPCS values in infarcted areas were similar in acute infarcts and in follow-up exams (p=0.8). In acute infarcts 74.6% of all in LGE infarcted segments (141/189) were correctly localized in polar plot strain maps compared to 44.4% (84/189) of infarcted segments detected by visual wall motion assessment only (p < 0.01). In follow-up exams, 81.5% of all in LGE infarcted segments (93/114 segments) were correctly localized in polar plot strain maps compared to 51.8% (59/114) of infarcted segments detected by visual wall motion assessment (p < 0.01). Conclusion Segmental circumferential strain derived from routinely acquired cine sequences detects nearly 75% acute infarcts and about 80% of infarcts in follow-up CMR and can potentially be used for scar identification based on non-contrast cine images, when gadolinium cant not be applied or LGE images are not available.