Optimal CW-Doppler derived parameter for the diagnosis of iatrogenic mitral stenosis during transcatheter edge-to-edge repair for mitral regurgitation
Authors: Kassar M , Madhkour R , Praz F , Hunziker L , Windecker S , Brugger N 
Published: October 2022

Abstract

Introduction
Transcatheter Edge-to-Edge repair (TEER) for mitral regurgitation (MR) is a minimal invasive alternative to surgery for high risk patients. One of the principal disadvantage is the risk of creating a stenosis (MS). The optimal parameter and its cut-off to monitor mitral valve area (MVA) during TEER is currently not defined and usually only the mean transmitral gradient (Gd) is used.

Method
116 patients with complete 3D MVA measurements and CW-Doppler derived mean and maximal diastolic transmitral Gd, and pressure half time (PHT) before the intervention and after each TEER device implantation were included in this study. A clinically significant MS was defined as a 3D MVA &lt;1.5 cm2 according to the ESC guidelines. Because the mean Gd is known to be extremely dependent on the heart rate (HR) this parameter was “normalized” for a frequency of 60/min: norm. mean Gd = (mean Gd/HR) × 60. The accuracy of the different CW-derived parameters to diagnose or predict a MS was evaluated using a ROC analysis.

Results
47% of the patients suffered from a secondary MR, 53% were treated with one device and 47% with two. According to the 3D MVA measurements, after one device 16 and after two devices 12 patients had a clinically significant MS. The ROC analyses for the diagnosis of a significant MS after one device (Figure 1) show a maximal AUC of 0.99 for PHT with an optimal cut-off of 151ms (sensitivity 94%, specificity 95%), followed by norm. mean Gd (AUC 0.96, 3.16mmHg, 100%, 82%), mean Gd (AUC 0.92, 3.6mmHg, 88%, 83%) and max. Gd (AUC 0.92, 8.5mmHg, 94%, 83%). Combining three different cut-offs (PHT 164ms or norm. mean Gd 4.7mmHg or max. Gd 12mmHg) a sensitivity of 100% and a specificity of 98% was achieved. The prognostic value of these same parameters to predict a MS after two devices was much less optimal according to the ROC analyses: PHT, AUC 0.82, 100ms, 83%, 59%; norm. mean Gd AUC 0.73, 2.8mmHg, 67%, 81%; mean Gd AUC 0.70, 2.4mmHg, 83%, 51%; max. Gd AUC 0.69, 8.4mmHg, 50%, 85%. The diagnostic value of the CW-derived parameters measured after the implantation of two devices to detect a MS was better (Figure 2): PHT, AUC 0.92, 142ms, 92%, 78%; norm. mean Gd, AUC 0.87, 3.4mmHg, 92%, 73%; mean Gd, AUC 0.81, 3.9mmHg, 92%, 71%; max. Gd AUC 0.74, 8.6mmHg, 83%, 66%. The cut-offs for PHT without false negative and with the maximal specificity were: 140ms (specificity 86%) to diagnose a MS after one device, 93ms (specificity 56%) to predict a MS after a second device implantation and 133ms (specificity 63%) to detect a MS after two devices.

Conclusion
PHT is the most accurate CW-derived parameter to diagnose or make a prognostic of clinically significant mitral stenosis after TEER. Given the possible disastrous consequence of a iatrogenic stenosis, these parameters should only be used with cut-offs offering a sensitivity of 100% and when a value above these limits is measured, then decisions should be based of 3D MVA measurements.

Funding Acknowledgement
Type of funding sources: None.