Assessment of myocardial fibrosis by late gadolinium enhancement imaging and biomarkers of collagen metabolism in chronic rheumatic mitral regurgitation.

BACKGROUND: In chronic rheumatic mitral regurgitation (CRMR), involvement of the myocardium in the rheumatic process has been controversial. Therefore, we sought to study the presence of fibrosis using late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMR) and biomarkers of collagen turnover in CRMR. METHODS: Twenty-two patients with CRMR underwent CMR and echocardiography. Serum concentrations of matrix metalloproteinase- 1 (MMP-1), tissue inhibitor of MMP-1 (TIMP- 1), MMP-1-to-TIMP-1 ratio, procollagen III N-terminal pro-peptide (PIIINP) and procollagen type IC peptide (PIP) were measured. RESULTS: Four patients had fibrosis on LGE-CMR. PICP and PIIINP concentrations were similar to those of the controls, however MMP-1 concentration was increased compared to that of the controls (log MMP-1 3.5 ± 0.7 vs 2.7 ± 0.9, p = 0.02). There was increased MMP-1 activity as the MMP-1-to- TIMP-1 ratio was higher in CRMR patients compared to the controls ( -1.2 ± 0.6 vs -2.1 ± 0.89, p = 0.002). CONCLUSIONS: Myocardial fibrosis was rare in CRMR patients. CRMR is likely a disease characterised by the predominance of collagen degradation rather than increased synthesis and myocardial fibrosis.

Congenital submitral aneurysm with rupture into the left atrium: assessment by 2D and 3D transesophageal echocardiography.

We describe two cases of congenital submitral aneurysms (SMAs) in which three-dimensional transesophageal echocardiography (3D TEE) proved useful to define the spatial extent of these aneurysms. In both cases, rupture into the left atrium was accurately delineated. 3D TEE was useful in case 1 as it depicted the precise site of rupture into the left atrium as well as pseudoprolapse of the P2 segment of the mitral valve. In case 2 it also localized the rupture into the left atrium in relation to the annulus to be adjacent to the anterolateral commissure. In addition, a cleft between the A1 and A2 scallops were identified and together with failure of the leaflets to coapt enabled the mechanisms contributing to the mitral regurgitation to be elucidated. Thus, imaging from the left atrial perspective using 3D TEE provided superior spatial anatomical delineation of the rupture and its relationship to the mitral valve, as well as accurate anatomical definition of the mitral leaflets. This information provides added benefit to the surgeon in planning a transatrial surgical repair of the SMAs. 3D TEE is superior to conventional 2D TEE in defining the spatial anatomy of SMAs as well as the mechanisms contributing to mitral regurgitation.