Lambl's Excrescences: Association with Cerebrovascular Disease and Pathogenesis

Abstract

Background: Lambl's excrescences (LEx) are detected by transesophageal echocardiography (TEE) and are characterized as thin, elongated, and hypermobile structures located at the leaflets' coaptation point of the heart valves. The association of LEx with cerebrovascular disease (CVD) is still undefined and yet patients with LEx and suspected CVD receive unproven effective antiplatelet or anticoagulant therapy or even undergo valve surgery. Also, the association of LEx with aging and atherogenic, inflammatory, or thrombogenic parameters has not been reported.

Methods: Seventy-seven patients with systemic lupus erythematosus (SLE) (71 women, age 37 ± 12 years) and 26 age- and sex-matched healthy controls (22 women, age 34 ± 11 years) prospectively underwent routine history and physical exam, transcranial Doppler, brain MRI, TEE, carotid duplex, and clinical and laboratory evaluations of atherogenesis, inflammation, platelet activity, coagulation, and fibrinolysis. Subjects without stroke/TIA on enrollment (with and without LEx) had a median follow-up of 57 months.

Results: On enrollment, 33 (43%) of 77 patients had CVD manifested as acute stroke/TIA (23 patients), cerebromicroembolism by transcranial Doppler (17 patients), or cerebral infarcts by MRI (14 patients). Mitral or aortic valve LEx were equally frequent in healthy controls (46%) as in patients with and without any CVD (39 and 43%), stroke/TIA (35 and 43%), cerebromicroembolism (41 and 42%), or cerebral infarcts (36 and 43%) (all p ≥ 0.72). Also, other mechanisms for CVD other than LEx such as Libman-Sacks vegetations, patent foramen ovale or interatrial septal aneurysm, aortic or carotid atherosclerosis, or thrombogenesis were found in ≥94% of patients with CVD. In addition, 36 subjects with and 44 without LEx had similar low incidence of stroke/TIA (1 (1.3%) and 2 (2.5%), respectively, p = 1.0) during follow-up. Finally, LEx were not associated with aging, atherogenic risk factors, atherosclerosis, inflammation, or thrombogenesis.

Conclusions: In this study, LEx are similarly prevalent in healthy controls and SLE patients, are not associated with CVD, and are not associated with pathogenic risk factors. Therefore, the study findings suggest that LEx may not be cardioembolic substrates, may not represent pathologic valve structures, and may not require therapy.

Figure 1. Lambl’s excrescences of the mitral and aortic valves

A. Two-dimensional (2D) TEE 4 and 2-chamber views of the mitral valve (bottom images) in a 21 year-old healthy female demonstrate a long, thin, and hypermobile Lambl’s excrescence located at the coaptation point and atrial side of normal mitral leaflets (Figure 1A video clip). Corresponding three-dimensional (3D) TEE atrial view of the mitral valve (top image) shows a Lambl’s excrescence at the coaptation point of the middle anterior and posterior mitral scallops (Figure 1A video clip). B. This aortic root 3D-TEE view of the aortic valve in a 44 year-old female with SLE demonstrates a Lambl’s excrescence (right arrow) on the tip and ventricular side of the left coronary cusp and a Libman-Sacks vegetation (left arrow) located on the tip and ventricular side of a thickened non-coronary cusp (Figure 1B video clip). C,D. This longitudinal 2-D TEE view (C) of the aortic valve in a 34 year-old female with SLE demonstrates a thin, elongated, and mobile Lambl’s excrescence at the coaptation point of the left and right coronary cusps prolapsing into the ventricular outflow tract during diastole (arrow) (Figure 1C video clip). Corresponding left ventricular outflow tract (LVOT) 3D-TEE systolic view (D) demonstrates a Lambl’s excrescence located on the ventricular side and tip of the left coronary cusp (Figure 1D video clip).

Figure 2. Histology of Lambl’s Excrescences

A. Gross anatomic view of a mildly sclerotic aortic valve with a thin (1 mm) and elongated (6 mm) Lambl’s excrescence (arrow) at the coaptation point and ventricular side of the left coronary cusp. B. Histology of longitudinal, cross-sectional, and oblique cuts of the Lambl’s excrescence demonstrate a core of fibroelastic, hypocellular, and avascular connective tissue covered by a single layer of endothelial cells.