Changes Of Left Ventricular Myocardial Strain In Acute ST-elevation Myocardial Infarction Patients And Its Relation To Microvascular Obstruction

Objective: To characterize the alteration in quantification of global left ventricular(LV)strain by cardiovascular magnetic resonance(CMR)feature tracking after acute ST-elevation myocardial infarction(STEMI),and to explore the relation to microvascular obstruction(MVO).Methods: The prospective study enrolled 30 patients with STEMI successfully treated with primary PCI who underwent CMR after 3.7±1.5days(baseline),91±4.8days(early follow-up),185±3.5 days(medium follow-up).Longitudinal global strains(GLS),circumferential global strains(GCS),global radial strains(GRS)and cardiac volume were measured by CVI 42 software based on cine sequences.MVO was assessed based on LGE sequence.According to the existence of MVO or not,all patients were divided into MVO(+)group and MVO(-)group.Mean values of GLS,GCS and GRS were compared between the two groups of patients using an independent-samples t-test.Means of baseline and follow-up measurements were compared using a paired t-test.LV remodeling is considered the end-systolic volume improvement more than 20%.Results: In this study,none of the patients had LV remodeling,according to the end-systolic volume improvement about 12.41%.Fourteen patients were classified as MVO(-)and sixteen patients as MVO(+).There was no significant difference in the clinical characteristics.At baseline,there were no significant differences of GRS,GCS and GLS between the two groups(P=0.24,0.13,0.29).At 3-month follow-up,GRS,GCS,GLS between MVO(+)and MVO(-)still make no significant differences(p=0.098,0.053,0.378),while the mean values of GRS,GCS,GLS significantly higher than that of baseline(p=0.008,0.005,0.036).At 6-month follow-up,the GLS between MVO(+)and MVO(-)still make no significant differences,while the GCS and GRS mean values of MVO(+)group make significant differences(p=0.019,0.014).Pearson correlation analysis showed a strong correlation between baseline GRS,GCS and left ventricular end-diastolicvolume.Conclusion: For acute STEMI patients without LV remodeling after PCI,the GRS,GCS and GLS of LV were all increased irrespective at 3-month follow-up of MVO existed or not,and the changes of GRS and GCS at 6-month follow-up in group without MVO was more obvious,Which may be the evidence of LV early remodeling.