Safety and Outcomes of Alcohol Septal Ablation Prior to Transcatheter Mitral Valve Replacement

Prevention of left ventricular outflow tract obstruction in transapical mitral valve replacement: the MitraCut procedure

BACKGROUND

The MitraCut procedure employs beating heart transapical (TA) cannulation and endoscopic scissors for dividing the anterior mitral leaflet (AML) to prevent left ventricular outflow tract (LVOT) obstruction in transapical transcatheter mitral valve replacement (TA-TMVR).

AIMS

We present the first multicentre experience of the MitraCut procedure prior to TA-TMVR to prevent LVOT obstruction.

METHODS

In 6 European centres, the clinical outcomes of all 13 high-risk patients who had undergone the MitraCut procedure during TA-TMVR procedures were retrospectively reviewed regarding technical success, procedural details and outcome.

RESULTS

The MitraCut procedure was successfully completed in 11 patients with 1 cutting attempt, while 2 patients had 2 cutting attempts, with an average procedure duration of 9.0±5.4 min. No patient demonstrated postoperative LVOT obstruction, and all mitral valve (MV) prostheses were competent throughout the follow-up period. However, 1 patient developed a MitraCut-related paravalvular leak (PVL; technical success rate: 12/13). The mean LVOT gradient was 3.9±4.4 mmHg directly after valve expansion and 3.6±3.1 mmHg at follow-up. In-hospital and 30-day mortality were 0%. One patient experiencing MitraCut-related PVL was successfully treated by interventional PVL closure (reintervention rate: n=1). One patient died at 47 days due to cardiac arrhythmia, unrelated to the AML-directed procedure. The mean follow-up at the time of data analysis was 52±34 days.

CONCLUSIONS

The MitraCut procedure was effective and reproducible for preventing potential LVOT obstruction in TA-TMVR patients during its initial exploration in 6 European hospitals. Considerations regarding the scissors' characteristics, their handling and cut length are mandatory for safe performance of the procedure.

Left ventricular outflow tract obstruction after transcatheter mitral valve replacement: a case report with a multifaceted approach

An 83-year-old woman was admitted to our center because of heart failure. Transthoracic echocardiography revealed severe mitral annular calcification resulting in a double mitral valve lesion. After discussion by the heart team, transcatheter mitral valve replacement with Tendyne (Abbott Structural, Santa Clara, CA, USA) was performed. Despite having a predicted neo-left ventricular outflow tract (LVOT) above the cut-off value, the patient developed clinically significant LVOT obstruction (LVOTO) refractory to medical treatment. This situation is often treated before the intervention, and dealing with LVOTO afterward can be challenging. After taking the patient's anatomy into consideration, we decided to perform alcohol septal ablation. Applying a combined strategy of medical treatment and intervention led to success. In this case report, we discuss this event and the strategies available for preventing and managing the condition.

Clinical characteristics and outcomes of alcohol septal ablation in the era of transcatheter valve interventions

BACKGROUND

The clinical efficacy and safety of alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy (HCM) have been well-established; however, less is known about outcomes in patients undergoing preemptive ASA before transcatheter mitral valve replacement (TMVR).

AIMS

The goal of this study is to characterize the procedural characteristics and examine the clinical outcomes of ASA in both HCM and pre-TMVR.

METHODS

This retrospective study compared procedural characteristics and outcomes in patient who underwent ASA for HCM and TMVR.

RESULTS

In total, 137 patients were included, 86 in the HCM group and 51 in the TMVR group. The intraventricular septal thickness (mean 1.8 vs. 1.2 cm; p < 0.0001) and the pre-ASA LVOT gradient (73.6 vs. 33.8 mmHg; p ≤ 0.001) were higher in the HCM group vs the TMVR group. The mean volume of ethanol injected was higher (mean 2.4 vs. 1.7 cc; p < 0.0001). The average neo-left ventricular outflow tract area increased significantly after ASA in the patients undergoing TMVR (99.2 ± 83.37 mm2 vs. 196.5 ± 114.55 mm2; p = <0.0001). The HCM group had a greater reduction in the LVOT gradient after ASA vs the TMVR group (49.3 vs. 18 mmHg; p = 0.0040). The primary composite endpoint was higher in the TMVR group versus the HCM group (50.9% vs. 25.6%; p = 0.0404) and had a higher incidence of new permanent pacemaker (PPM) (25.5% vs. 18.6%; p = 0.3402). The TMVR group had a higher rate of all-cause mortality (9.8% vs. 1.2%; p = 0.0268).

CONCLUSIONS

Preemptive ASA before TMVR was performed in patients with higher degree of clinical comorbidities, and correspondingly is associated with worse short-term clinical outcomes in comparison to ASA for HCM patients. ASA before TMVR enabled percutaneous mitral interventions in a small but significant minority of patients that would have otherwise been excluded. The degree of LVOT and neoLVOT area increase is significant and predictable.

Left Ventricular Outflow Tract Modification for Transcatheter Mitral Valve Replacement

Left ventricular outflow tract (LVOT) obstruction is a life-threatening complication of transcatheter mitral valve replacement. In-depth analysis of pre-procedural computed tomography enables accurate prediction of this risk. Several techniques for LVOT modification, including Laceration of the Anterior Mitral leaflet to Prevent Outflow ObtructioN, preemptive alcohol septal ablation, preemptive radiofrequency ablation, and Septal Scoring Along the Midline Endocardium, have been described as effective strategies to mitigate this risk. This review aims to explore the indications, procedural steps, and outcomes associated with these LVOT modification techniques.

Preemptive alcohol septal ablation prior to transcatheter mitral valve replacement

BACKGROUND

Alcohol septal ablation (ASA) has been shown to increase the neo-left ventricular outflow tract (LVOT) area before transcatheter mitral valve replacement (TMVR) but there is little literature on its success and use with dedicated devices.

AIMS

To describe our experience with preemptive ASA to increase the predicted neo-LVOT area and its utility with both dedicated TMVR devices and balloon-expandable valves.

METHODS

All patients who underwent ASA for TMVR candidacy in our center between May 2018 and October 2022 and had computed tomography (CT) scans done before and after ASA were included. Each CT was assessed for the minimum predicted neo-LVOT area at end-systole, using a virtual valve of the desired TMVR device for each patient. The primary outcome was an increase in the predicted neo-LVOT area after ASA that was deemed sufficient for safe implantation of the desired TMVR device. The secondary outcome was the absence of acute LVOT obstruction after TMVR.

RESULTS

A total of 12 patients underwent ASA and all but 1 (n = 11, 91.6%) achieved the primary outcome of having sufficient predicted neo-LVOT area to proceed with TMVR. The mean increase in neo-LVOT area after ASA was 126 ± 64 mm2 (median 119.5, interquartile range: 65.0-163.5 mm2 ). Two patients (16.7%) required a permanent pacemaker after ASA. Nine patients went on and underwent TMVR with their respective devices and none had LVOT obstruction after the procedure. Among the remaining three patients, one had insufficient neo-LVOT clearance after ASA, one had unrelated mortality before TMVR, and one had advanced heart failure before TMVR.

CONCLUSION

In appropriately selected patients and at centers experienced with ASA, preemptive ASA can achieve sufficient neo-LVOT clearance for TMVR with a variety of devices in approximately 90% of patients.