Aims: To determine changes of global longitudinal strain (GLS) and their predictors in relation to classical echocardiographic parameters of left ventricular (LV) function, over 1 year, in consecutive patients with myocardial infarction (MI) and initially normal or impaired LV ejection fraction (EF).
Methods and results: A total of 285 patients with MI prospectively included in the REBUS (RElevance of Biomarkers for future risk of thromb-oembolic events in UnSelected post-myocardial infarction patients) study underwent echocardiography within 72 h from admission and after 1 year. At baseline, 213 (74.7%) of MI patients had a normal EF (≥52% in men or ≥54% in women), but in 70.4% of them, an impaired GLS ( ≥ -18.0%) was observed. During 1-year follow-up, in patients with normal EF at baseline, GLS improved from -15.8% to - 17.4% (10.1% relative change); EF decreased from 62.5% to 59.9% (4.0% relative change); indexed end-diastolic volume, indexed end-systolic volume, and indexed stroke volume increased with 15.6%, 24.8%, and 10.0% of relative change, respectively (P < 0.001 for all the comparisons). In the whole cohort, initial impairment of LV function [by EF, wall motion score index (WMSI), or GLS], male gender, non-smoking, and treatment with beta-blockers were the independent predictors of GLS improvement. In the group with initially impaired EF, over 1 year GLS improved from -11.9% to - 14.8% (24.4% relative change) and EF from 44.6% to 52.6% (18.2% relative change) (P < 0.001 for both). Improvement in GLS significantly correlated with EF increase in the group with impaired EF (r = -0.41, P = 0.001) but not in the patients with normal EF (r = -0.14, P = ns).
Conclusions: Despite diveregent evolution of GLS compared with EF and ventricular volumes, one year after MI GLS significantly improved in patients with initially both normal and impaired EF. Initial impairment of LV function (by EF, WMSI, or GLS), male gender, non-smoking, and treatment with beta-blockers were independent predictors of GLS improvement. LV remodelling was present even in patients with normal EF at baseline and during follow-up, confirming limited functional assessment by EF alone.