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Echocardiographic evaluation of left ventricular function in ST-segment elevation myocardial infarct patients Focus on global longitudinal strain

 

Kim Munk

Summary

In patients with ST-segment elevation myocardialinfarction (STEMI), the damage to the left ventricle,reflected in the left ventricular systolic function is acritical determinant of an adverse prognosis.In the present thesis, the effect on left ventricularfunction, of remote ischemic conditioning, areperfusion modifying strategy aiming atattenuating ischemia-reperfusion injury, isevaluated. Secondly, we evaluate the utility ofspeckle tracking global longitudinal systolic strain(GLS), a measure of global long axis LV systolicfunction, in determining infarct size and predictingadverse events in survivors of STEMI.We found no overall difference in LV function as aresult of remote ischemic conditioning, but highrisk patients with culprit lesion in LAD´s vascularbed and those with extensive myocardial area atrisk benefitted from this adjunctive treatment interms of preserved LV function.When obtained on day one after revascularization,GLS was comparable to wall motion scoring andbetter than volumetric LV function indices and hadincremental value independent of conventionalechocardiographic systolic function measures inreflecting the resultant infarct size.When obtained after 30 days of follow up, wallmotion scoring was a better indicator of the infarctsize, while GLS was comparable with ejectionfraction and LV end-systolic volume in reflectingthe myocardial injury inflicted by a STEMI.For early risk assessment after STEMI, wall motionscoring and GLS both were superior to LV ejectionfraction and end systolic volume. Moreover, GLSyielded independent value of ejection fraction andLV end-systolic volume in predicting adverseevents. With the wall motion score index known,the independent prognostic value of GLS wasborderline significant.In conclusion, the results of this thesis demonstratethat remote ischemic condition may confer clinicalrelevant cardio protection to high risk STEMIpatients. Furthermore, GLS, in the early settingafter revascularisation for STEMI, may supplementconventionally used echocardiographic systolicfunction indices in reflecting the resultant infarctsize, and for assessing the future risk of developingadverse cardiac events. Therefore, GLS could beconsidered for implementation in the routineechocardiographic examination early after aSTEMI. The role of GLS for assessment of LVfunction on follow up seems less obvious.