Influence of the degree of mitral annular calcification in the variation of mean transmitral gradient in early post-procedural transcatheter aortic valve implantation

Abstract Background Patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI) have frequently severe mitral annulus calcification (MAC) that can cause mitral stenosis. However, the left ventricular (LV) pressure overload caused by the aortic stenosis may reduce the transmitral pressure gradient and the severity of mitral stenosis may be underestimated. Purpose To evaluate the frequency of severe MAC in patients undergoing TAVI and describe the changes in transmitral pressure gradient after TAVI according to the severity of the MAC. Methods Patients with severe aortic stenosis undergoing TAVI who had cardiac computed tomography data to analyse the severity of MAC and a transthoracic echocardiogram prior to the intervention and at hospital discharge were included. The severity of MAC was defined as mild MAC (3 points or less), moderate MAC (4 to 6 points), and severe MAC (7 points or more) based on the distribution of the calcification of the mitral valve (thickness, circumferential distribution, involvement of the trigones and leaflets). The changes in transmitral pressure gradient were evaluated with linear multivariate regression adjusting for age and sex. Results A total of 203 patients (median age 81 years, 40% male) with severe AS who successfully underwent TAVI were included. According to the classification of MAC severity by cardiac CT, 55 (27%) patients had no MAC, 57 (28%) mild MAC, 55 (27%) moderate MAC, and 36 (18%) severe MAC. The groups were comparable in terms of demographics and clinical characteristic. The NT-proBNP increased progressively with the severity of MAC. Transthoracic echocardiography was performed at a median of 43 days before TAVI and 3 days after TAVI. In terms of echocardiographic characteristics at baseline, there were no statistically significant differences across theg roups except from transmitral pressure gradient, which was significantly higher as the severity of MAC increased on CT . After TAVI, there was no significant change in mean transmitral pressure gradient in patients without MAC. In contrast, patients with mild, moderate and severe MAC had significant increases in trasmitral pressure gradient following TAVI, with greater changes associated with increasing severity of MAC (mild p0.0001, moderate p 0.0007, severe p0.0060) Conclusions In patients with severe aortic stenosis and severe MAC, the transmitral pressure gradient increases significantly after TAVI. Therefore, TAVI may unmask significant mitral stenosis that may impact the results of TAVI at mid term follow-up.