Protective effect of severe mitral regurgitation (MR) against left atrial thrombus (T) formation has been documented. It was also proposed that severe MR could prevent T formation in the left ventricle (LV) in the presence of systolic LV dysfunction (LVD). The purpose of this study is to investigate whether ischemic MR prevents T formation within the LV in patients with LVD. Study population comprised 1313 pts (M 1133, F 180, age 56±18 years) with is-chemic LVD documented by coronary angiography and left ventriculography. None of the patients had history of chronic anticoagulation. Epicardial coronary arteries were normal in 91 patients, and single-vessel, two-vessel, and triple-vessel disease were documented in 328, 330, and 564 patients, respectively. Global systolic LVD was defined as EF < 0.50. Severity of the angiographic MR was graded as mild, moderate and severe. Dyskinesia and aneurysm related to septal (S), apical (A) and/or anterolateral (AL) wall segments were found in 394 and 470 pts, respectively. Dyskinesia and aneurysm associated with posterobasal (PB), posterolateral (PL) and /or inferior (I) wall segments were detected in 110 and 181 pts, respectively. Ischemic dilated cardiomyopathy was documented in 158 patients. Mural LVT and severe ischaemic MR were detected in 191 (14.5 %) and 125 (9.5%) patients, respectively. Overall incidence of LVT was found to be lower in patients with MR as compared to those without MR (4% vs 15.6%, OR: 0.2, p<0.001). In comparison to the absence of MR, severe MR was associated with a lower incidence of LVT in patients with ischemic dilated cardiomyopathy (6.8% vs 34.2%, OR: 0.19, p<0.001) and in patients with segmentary LVD (2.5% vs 13.7%, OR: 0.2, p<0.01). There was a significant difference in reference to presence of severe MR in patients with aneurysm (3% vs 18%, OR: 0.14, p<0.0001), and a nonsignificant difference in patients with dyskinesia (4.7% vs 16%, OR: 0.26, p=0.1) related to A, AL, S wall segments. However, MR had no impact on incidence of LVT in the group with aneurysm or dyskinesia related to PB, I, or PL segments (3.7% vs 3%, OR: 1.2, p>0.05).
CONCLUSIONS (1) Severe MR seems to prevent mural LVT formation both in patients with ischemic dilated cardiomyopathy and in patients with aneurysm related to anterior LV wall segments, and (2) this protective effect of severe MR against LVT formation may be associated with diastolic volume overloading which may offset stagnation and procoagulant state within the LV with systolic dysfunction.
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