Severe Mitral Regurgitation May Prevent Mural Thrombus Formation within the Left Ventricle with Systolic Dysfunction.

Abstract

SUMMARYThe protective effect of severe mitral regurgitation (MR) against left atrial thrombus formation has been well documented. It was also proposed that severe MR may prevent thrombus formation within the left ventricle (LV) with systolic dysfunction. Therefore, we investigated whether ischemic MR prevents thrombus formation within the LV in patients with systolic dysfunction. The study population was comprised of 1313 patients (1133 males, 180 females, age 56±18) with ischaemic LV dysfunction documented by coronary angiography and left ventriculography. None of the patients had a history of chronic anticoagulation. Epicardial coronary arteries were normal in 91 patients, and single-vessel, two-vessel, and triple-vessel disease were detected in 328, 330, and 564 patients, respectively. Left ventricular thrombus and severe MR were detected in 191 (14.5%) and 125 (9.5%) patients, respectively. Overall incidence of LV thrombus was lower in patients with severe MR than in patients without severe MR (4% vs 15.6%, OR: 0.2, P<0.001).Severe MR compared with absence of severe MR was associated with a lower incidence of LV thrombus both in patients with ischemic dilated cardiomyopathy (6.8% vs 34.2%, OR: 0.19, P<0.001), and in patients with aneurysm (3% vs 18%, OR: 0.14, P<0.0001) involving anterolateral, septal and/or apical LV segments. A similar trend without statistical significance was also observed in patients with dyskinesia (4.7% vs 16%, OR: 0.26, P=0.1) related to anterolateral, septal and/or apical LV segments. However, MR had no impact on the incidence of LV thrombus in patients with aneurysm or dyskinesia related to posterior and/or inferior segments (3.7% vs 3%, OR: 1.2, P>0.05).In conclusion, severe MR seems to prevent LV mural thrombus formation in patients with ischemic dilated cardiomyopathy, and in patients with aneurysm related to anterolateral, septal, and/or apical LV segments. This relative risk reduction may be associated with diastolic volume overloading due to severe MR which may overcome stagnation and a procoagulant state within the LV with severe systolic dysfunction. (Jpn Heart J 2002; 43: 495-503)

Clinical Characteristics and Risk Factors of Left Ventricular Thrombus after Acute Myocardial Infarction

“…[ 15 ] and Ozdemir et al . [ 16 ] inferred that severe MR may have a protective role in LVT formation, as it was identified only in the non-LVT group. However, other studies with AMI patients reported by Ascione et al .…”

A Model Incorporating Some of the Mechanical and Biochemical Factors Underlying Clot Formation and Dissolution in Flowing Blood

“…The existent data support this hypothesis (Ozdemir et al, 2002). However, there are two circumstances in which the native ventricles (typically, the left) may form intracavitary thrombus.…”

“…low and slow flow with global or regional ventricular hypokinesis. Supporting this hypothesis, interestingly, it is that, in patients with mitral regurgitation in which the left ventricle is "auto" afterload-reduced by a parallel low afterload ejection pathway, the incidence of cavitary thrombus is decreased (Ozdemir et al, 2002). Second, and more importantly as an extreme case of regional ventricular dysfunction, ventricular aneurysm (most commonly in the left, and a result of prior myocardial infarction) characterized by regional ventricular wall dilatation and thinning with paradoxical expansion during ventricular systole (dyskinesis) is associated with a high rate of intracavitary thrombus formation (Natterson et al, 1995).…”

Risk Factors for Left Ventricular Thrombus Formation in Patients with Dilated Cardiomyopathy

“…Ozdemir et al reported that patients with DCM accompanying severe MR had a lower incidence of LVT (6.8 vs. 34.2%). 8 LVT in that study was assessed by left ventriculography instead of TTE. Kalaria et al showed that the prevalence of DCM with MR was comparable between the LVT and LVT absent groups.…”