P300Ischemic mitral regurgitation in response to the increase of closing force in anterior and inferior myocardial infarction


    loading  Checking for direct PDF access through Ovid

Abstract

Purpose: This study was conducted to explore the role of closing force in the mechanism of ischemic mitral regurgitation (IMR) in anterior (ant) and inferior (inf) myocardial infarction (MI) through the low dose dobutamine echocardiography (LDSE).Methods: Forty two patients (ant-MI: inf-MI=20:22, age=62 ± 14yrs) with significant (> grade1) IMR were enrolled and underwent LDSE (peak dose: 10μg/kg/min). Left ventricle end diastolic volume (LVEDV), end systolic volume (LVESV) and LV ejection fraction (LVEF) were calculated by the modified Simpson's method. The MR severity was defined by effective regurgitation orifice area (EROA) using conventional PISA method. Peak systolic trans-mitral valvular pressure gradient (trans-MV PG), reflecting closing force of the mitral valve, was estimated by measuring peak velocity of MR jet. Mitral valve tenting area (MVTa) and tenting height (MVTh) were also measured. All variables were acquired before and after stress.Results: In the baseline data, there were significant differences between ant and inf-MI in LVEDV (127 ± 42 vs. 85 ± 25ml, p=0.02), LVESV (79 ± 26 vs. 45 ± 15ml, p=0.03), LVEF (36 ± 5 vs. 45 ± 3%, p=0.01) MVTa (2.0 ± 0.5 vs. 1.2 ± 0.4 cm2, p=0.03), and MVTh (1.1 ± 0.26 vs. 0.72 ± 0.25cm, p=0.02). However, there was no significant difference in EROA (17 ± 3.6 vs. 19 ± 4.5mm2, p=0.54) between two groups. In ant-MI, all patients showed central MR jet on the apical 3 chamber view. Whereas in inf-MI, only 5 patients showed central MR jet, rest of patients (n=17) revealed posterior directed MR jet.During stress, LVESV (79 ± 26 vs. 67 ± 14ml, p=0.03), (45 ± 15 vs. 40 ± 11ml, p=0.035), MVTa (2.0 ± 0.5 vs. 1.7 ± 0.12cm, p=0.03), (1.2 ± 0.4 vs. 1.02 ± 0.15cm2, p=0.02) and MVTh (1.1 ± 0.26 vs. 9.9 ± 0.08cm, p=0.03), (0.72 ± 0.25 vs. 0.67 ± 0.05cm, p=0.04) significantly decreased in both ant and inf-MI. LVEF (36 ± 5 vs. 43 ± 5%, p=0.01), (45 ± 3 vs. 52 ± 7%, p=0.02) and trans-MV PG (110 ± 44 vs. 145 ± 35mmHg, p=0.001), (116 ± 32 vs. 148 ± 27mmHg, p=0.001) showed significant increase during stress in both ant and inf-MI, reflecting the increase of closing force. EROA significantly decreased in ant-MI (17 ± 3.6 vs. 9 ± 2.5mm2, p=0.01) during stress while it significantly increased in inf-MI (19 ± 4.5 vs. 21 ± 3.2mm2, p=0.025), particularly in patients showing posterior directed MR jet.Conclusion: This study suggests that the closing force plays a different role in the mechanism of IMR between ant and inf-MI. The higher closing force gets, the less IMR develops in ant-MI. On the contrary, the higher closing force gets, the more IMR develops in inf-MI.

    loading  Loading Related Articles