Left ventricular function and coronary microcirculation in patients with mild reduced ejection fraction after STEMI

Background The characteristics of heart failure (HF) with mildly reduced ejection fraction (EF) (HFmrEF) overlap with those of HF with reduced EF (HFrEF) and HF with preserved EF (HFpEF) and need to be further explored. This study aimed to evaluate left ventricular (LV) function and coronary microcirculation in patients with mildly reduced ejection fraction after acute ST-segment elevation myocardial infarction (STEMI). Methods We enrolled 119 patients with STEMI who had undergone speckle tracking imaging and myocardial contrast echocardiography during hospitalization from June 2016 to June 2021. They were classified into normal, HFmrEF, and HFrEF groups according to their left ventricular EF (LVEF): >= 50%, 40-50%, and <= 40%, respectively. The data of the HFmrEF group were analyzed and compared with those of the normal and HFrEF groups. Results HFmrEF was observed in 32 patients (26.9%), HFrEF in 17 (14.3%), and normal LVEF in 70 patients (58.8%). The mean global longitudinal strain (GLS) of all patients was - 11.9 +/- 3.8%. The GLS of HFmrEF patients was not significantly different from that of the HFrEF group (- 9.9 +/- 2.5% and - 8.0 +/- 2.3%, respectively, P = 0.052), but they were both lower than that of the normal group (- 13.8% +/- 3.5%, P < 0.001). The HFmrEF group exhibited significantly poorer myocardial perfusion index (1.24 +/- 0.33) than the normal group (1.08 +/- 0.14, P = 0.005) but displayed no significant difference from the HFrEF group (1.18 +/- 0.19, P = 0.486). Moreover, a significant difference in the incidence of regional wall motion (WM) abnormalities in the three groups was observed (P = 0.009), and the WM score index of patients with HFmrEF was 1.76 +/- 0.30, similar to that of patients with HFrEF (1.81 +/- 0.43, P = 0.618), but poorer than that in the normal group (1.33 +/- 0.25, P < 0.001). Conclusions GLS is a more sensitive tool than LVEF for detecting LV systolic dysfunction. The LV systolic function, coronary microcirculation, and WM in patients with HFmrEF was poorer than that of patients with normal LVEF, but comparable to that in patients with HFrEF. Patients with HFmrEF after STEMI require more attention and appropriate management.