Mitral annular remodeling after transmural myocardial infarction is associated with new-onset dilatation of the left cardiac chambers and reduced left atrial function

Abstract Background Dilatation of the mitral annulus (MA) is a main contributor to development of functional mitral regurgitation. The impact of left chamber remodeling following a myocardial infarction on the MA size and function has so far not been thoroughly explored. Purpose We aimed to investigate how altered size and function of the left atrium (LA) and left ventricle (LV) impacts the MA in patients with transmural myocardial infarction. Methods In a prospective, longitudinal observational study, patients admitted with ST-elevation myocardial infarction (STEMI) were examined during admission (baseline visit) and 1 year after the event (follow-up visit). The LV, LA and MA size and function were assessed by 3D echocardiography at both visits. Changes in MA area during the cardiac cycle were assessed using semi-automatic annotations. Significant MA remodeling was defined as an area increase at follow-up of 15% or more. The cohort was divided into two groups: patients with (n=16) or without (n=71) significant MA remodeling. Results One year after STEMI, patients without MA remodeling presented no change in LV end-diastolic volume (161 ml to 163 ml) or maximum LA volume (61 ml to 60 ml) compared to baseline. Moreover, they had improved LV ejection fraction (47% to 53%) and LV global longitudinal strain (-10.6% to -13.3%), as well as improved LA emptying fraction (47% to 51%), LA reservoir strain (14.6% to 17.7%) and LA contractile strain (-6.1% to -8.7%) (all p≤0.001) On the contrary, patients with significant MA remodeling had larger LV end-diastolic (157 ml to 175 ml) and maximum LA volume (64 to 74 ml) (both p