New echocardiographic screening tool for left ventricular tract obstruction risk assessment in TMVR

Transcatheter mitral valve replacement (TMVR) is an alternative to conventional surgery to treat severe mitral disease but its use is limited by the risk of left ventricular outflow tract obstruction (LVOTO). Screening depends on ECG-gated computed tomography (CT) that is not widely available and requires contrast. We developed and validated a transthoracic echocardiographic (TTE) method to assess the risk of LVOTO after TMVR with the Tendyne System.

We measured the LVOT longitudinal area on preoperative TTE dataset of patients screened for TMVR. The LVOT was measured as the box-area included by the aortic valve annulus, the anterior mitral leaflet (AML), the c-septum distance line, and the respective length of the AML on the interventricular septum. We analyzed the correlation between the TTE LVOT-box and the CT-measured neoLVOT area. Prediction performance for eligible patients was tested with ROC curves.

Thirty-nine patients were screened, out of 14 patients (36%) not eligible for TMVR, 8 had risk of LVOTO. We found a linear correlation between the TTE LVOT-box and the CT-measured Neo-LVOT (r = 0.6, p = 0.002). ROC curve showed that the method is specific and sensitive and the cut-off value of the measure LVOT-box is 350 mm².

The proposed method is reliable to evaluate the risk of LVOTO after TMR with the Tendyne System. It is quick and easy and can be used as a first-line assessment in the outpatient clinic. Patients with LVOT-box <350 mm² should not be further screened with ECG-gated cardiac CT.