Association of Feature-Tracking Cardiac Magnetic Resonance Imaging Left Ventricular Global Longitudinal Strain With All-Cause Mortality in Patients With Reduced Left Ventricular Ejection Fraction
Authors: Simone Romano, Robert M. Judd, Raymond J. Kim, Han W. Kim, Igor Klem, John Heitner, Dipan J. Shah, Jennifer Jue, Brent E. White, Chetan Shenoy, Afshin Farzaneh-Far
Journal: Circulation (2017)

Direct assessment of myocardial fiber deformation with echocardiographic global longitudinal strain (GLS) has shown promise in providing prognostic information that is incremental to ejection fraction (EF) in patients with left ventricular dysfunction. 1 Cardiac magnetic resonance (CMR) imaging has now evolved into a major tool for evaluation of patients with left ventricular dysfunction, providing precise measurements of EF and viability assessment with late gadolinium enhancement (LGE).Recent development of CMR feature-tracking techniques now allow assessment of GLS from standard cine CMR images without the need for specialized pulse sequences or additional scanning time. 2 We therefore hypothesized that CMR feature-tracking derived GLS may provide incremental prognostic information in these patients.Consecutive patients (n=470) undergoing CMR with both cine and LGE imaging for evaluation of ischemic or nonischemic dilated cardiomyopathy with EF <50% were included in this retrospective study.Comprehensive phenotyping, including clinical history, imaging, and cardiac catheterization, classified 330 individuals with ischemic and 140 with nonischemic cardiomyopathy.Institutional review board approval was obtained.Steady-state free-precession cine images were acquired in multiple short-axis and 3 long-axis views.LGE imaging was performed 10 to 15 minutes after Gadolinium contrast (0.15 mmol/kg) administration using a 2D-segmented gradient echo inversion recovery sequence in the same views used for cine CMR.The size of LGE (as a percentage of total left ventricular myocardium) was determined as previously described. 3Endocardial left ventricular contours were manually traced (by a single physician who was blinded to patient information and outcomes) in all 3 long-axis cine views to derive GLS using the Qstrain feature-tracking package (Medis Medical Imaging Systems).Patients were followed for the primary outcome of all-cause mortality using the US Social Security Death Index.Time to event was calculated as the period between the CMR study and death.Patients who did not experience the primary outcome were censored at the time of assessment.Analyses were performed using STATA (StataCorp).The mean age of the study population was 60±15years.Sixty-nine percent were male and 30% had diabetes mellitus.The mean EF was 34.2±9.8%.Mean GLS was -10.4±4.6%.Median GLS was -10.3% (interquartile range, -7.1 to -13.6%).During a median follow-up of 4.1years (interquartile range, 3.5-4.8years), 93(19.8%)patients died.By Kaplan-Meier analysis, the risk of death increased significantly with worsening tertiles of GLS (log-rank P<0.0001) (Figure A) as well as with increasing tertiles of LGE size (log-rank P=0.01) (Figure B).LGE size demonstrated a significant univariable association with death (hazard ratio [HR], 1.03 per %; 95% confidence interval [CI], 1.01-1.05;P<0.001).Likewise, EF demonstrated a significant univari-