Transfemoral Transcatheter Aortic Valve-in-Valve Implantation for Aortic Valve Bioprosthesis Failure With the Fully Repositionable and Retrievable Lotus Valve: A Single-Center Experience

Abstract: Objective. To report a first case series of the Lotus valve (Boston Scientific) for the treatment of surgical aortic bioprosthesis failure. Background. Valve-in-valve (VIV) transcatheter aortic valve implantation (TAVI) is an established management option for surgical aortic bioprosthesis failure. Although TAVI has proven efficacious, complications relating to suboptimal valve implantation have been reported in approximately 5% of patients. The Lotus valve is fully repositionable and retrievable, and therefore enables complete assessment of valve function prior to definitive deployment. However, data supporting its use for this indication are limited. Methods. Consecutive patients who underwent transfemoral VIV-TAVI at John Radcliffe Hospital between January 2015 and December 2016 were retrospectively analyzed. Procedural and 30-day outcomes were reported in accordance with Valve Academic Research Consortium-2 (VARC-2) definitions. Results. Seven patients underwent VIV-TAVI with the Lotus valve. Device success according to VARC-2 criteria was achieved in 6 of the 7 patients. Following implantation, transvalvular hemodynamics were acceptable, with a mean gradient of 11.9 ± 6.6 mm Hg. All patients had mild or no residual aortic regurgitation. Specifically, no patient required further valve-related intervention, or suffered myocardial infarction, stroke, or acute kidney injury stage 2 or 3. There were no deaths during the follow-up period. Conclusions. Transfemoral VIV-TAVI for the treatment of surgical aortic bioprosthesis failure with the Lotus device appears to be safe and is associated with no significant residual aortic regurgitation, and offers favorable transvalvular hemodynamics at 30-day follow-up. 

J INVASIVE CARDIOL 2017;29(9):315-319. Epub 2017 July 15.

Key words: aortic regurgitation, valve-in-valve, TAVI, new device

Surgical aortic valve replacement (SAVR) remains the treatment of choice for patients presenting with symptomatic aortic valve pathology who are considered low surgical risk.^1-3 There has been a trend toward the greater use of bioprosthetic valves due to improved durability and no requirement for formal anticoagulation.⁴ However, surgical bioprostheses do have a failure rate either due to stenosis or regurgitation over time, with durability reported at between 10-20 years.^5-7 These patients often have multiple comorbidities and redo open surgical intervention is associated with significant risk.⁸ 

Transcatheter valve-in-valve (VIV) treatment has been shown to be safe and efficacious, and is now an accepted treatment option for the management of this patient group.^9-11 However, in spite of increased understanding of surgical bioprostheses^10,12 and greater operator and institutional experience, VIV procedures are still associated with risks, including coronary obstruction,^13,14 clinically significant residual aortic regurgitation (AR) due to suboptimal position,⁹ and device malposition.⁹ The Lotus valve (Boston Scientific) is currently the only commercially available transcatheter prosthesis that is fully repositionable and retrievable when fully deployed.¹⁵ These properties make its use for VIV procedures particularly attractive, enabling complete assessment of valve function and potential complications (eg, obstruction of the coronary ostia) prior to definitive deployment. There are limited data supporting its use for this indication.^16,17 

We present the first larger case series of consecutive patients who received the fully repositionable and retrievable Lotus transcatheter aortic valve implantation (TAVI) device for the treatment of degenerated surgical aortic bioprosthesis.

Methods

Study population. All patients who underwent transfemoral VIV-TAVI for failed surgical aortic bioprosthesis at the John Radcliffe Hospital, Oxford, United Kingdom between January 2015 (first Lotus valve implant) and December 2016 were retrospectively analyzed. All patients underwent preprocedural transthoracic echocardiography to confirm the diagnosis and computed tomography (CT) to aid in procedural planning, which was performed with dedicated software for measurements of peripheral vasculature and aortic anatomy (3mensio v. 7.0 software; Pie Medical Imaging). All patients were discussed by a multidisciplinary heart team and were considered to be at elevated risk of redo open-heart surgery. Bioprosthetic aortic valve failures were categorized as stenotic, regurgitant, or mixed according to the recommendations of the American Society of Echocardiography.¹⁸ Patient characteristics and details of previous surgical bioprostheses were noted. All patients gave their informed consent for the study. 

The Lotus valve. The Lotus valve consists of a woven nitinol-framed bioprosthesis with bovine pericardial leaflets, and is premounted on a catheter delivery system. The device is positioned using a mechanical deployment device and is designed to enable repositioning and complete retrieval even after the valve is fully expanded and locked in its final position. The design also incorporates an “adaptive seal” at the distal end of the prosthesis to minimize the occurrence of paravalvular leak. The device requires the insertion of a 20-22 Fr transfemoral sheath and is available in 23 mm, 25 mm, and 27 mm sizes.

Procedure. All patients underwent implantation of the Lotus valve via the transfemoral route with percutaneous ultrasound-guided puncture sites closed with Proglide suture-based closure devices (Abbott Laboratories) when possible, or facilitated by vascular surgical cut-down. Prosthesis sizing was at the operator’s discretion based upon the multislice CT findings, the type and size of the surgical bioprosthesis in situ, and available recommendations.¹⁹ All procedures were carried out under general anesthesia or conscious sedation provided by a cardiac anesthetist. Unfractionated heparin was administered periprocedurally, aiming for an activated clotting time (ACT) of 300 sec. TAVI was performed under fluoroscopic and echocardiographic guidance. Briefly, after crossing the surgical bioprosthesis, a Safari stiff wire (Boston Scientific) was positioned in the left ventricle over which the Lotus device was delivered without predilation. Valve position and function were fully evaluated prior to definitive deployment (Figure 1). After valve deployment, aortic valve hemodynamics were assessed by echocardiography with peak and mean transvalvular gradients noted in addition to the AR grade, in keeping with current guidelines.²⁰ Following the procedure, patients were administered dual-antiplatelet therapy (aspirin 75 mg daily and clopidogrel 75 mg daily) for a minimum period of 3 months. 

Clinical follow-up. Procedural and 30-day outcomes were prospectively collected in a dedicated TAVI database and follow-up was conducted either by clinic visits or telephone consultations. All definitions of the clinical endpoints used were in accordance with the Valve Academic Research Consortium-2 (VARC-2) definitions²¹ and were independently adjudicated by at least two interventional cardiologists. Other information collected included the severity of AR following TAVI (by aortography or echocardiography) and the requirement for permanent pacemaker (PPM) implantation.

Statistical analysis. Continuous variables are expressed as mean ± standard deviation (SD). Normality of each continuous variable was tested with the Kolmogorov-Smirnov test. Categorical variables are presented as numerical values and percentages. Analyses were performed with SPSS v. 21.0 (SPSS, Inc) and GraphPad Prism v. 5.0 (GraphPad).

Results

Patient population. Seven patients underwent VIV-TAVI with transfemoral implantation of the Lotus valve for surgical aortic bioprosthesis failure. Baseline patient characteristics are summarized in Table 1. Five patients were male (71.4%) and mean age was 80.3 ± 3.7 years. The mean Logistic EuroScore was 30.2 ± 16.1 and Society of Thoracic Surgeons (STS) score for mortality was 3.7 ± 1.1.

Baseline valve characteristics are summarized in Table 2. The xenografts were stented in 6 patients (85.7%) and stentless in 1 patient. Sizes of surgical bioprosthetic valves ranged from 21 mm to 27 mm. Two patients (28.6%) presented with severe aortic stenosis, 4 patients (57.1%) presented with mixed stenosis and regurgitation, and 1 patient (14.3%) presented with severe AR. The median time from index surgical valve implantation to VIV-TAVI was 11 years (range, 8-22 years). 

Procedural characteristics and outcomes. The Lotus valve was successfully implanted in all patients (Table 3). Postdilation was not required in any patient following definitive deployment of the valve. There were no instances of coronary obstruction, myocardial infarction, stroke, aortic rupture, vascular injury, or bleeding complication. There was no requirement for emergent surgical intervention. 

Five patients (71.4%) were treated under local anesthesia and conscious sedation. One patient underwent elective surgical vascular cut-down of the femoral artery to facilitate vascular access in view of severe calcification of the peripheral vasculature. 

The valve failed to deploy in 1 patient (#2) in spite of an excellent initial position. The device was completely recaptured and a second identical device was implanted without further complication. The Lotus valve was fully resheathed in 1 patient (#5) and repositioned due to initial moderate AR with residual mild AR following deployment at the optimal height. One patient required PPM implantation for complete heart block on day 4 following valve implantation. 

At discharge, echocardiography demonstrated a mean transvalvular peak gradient of 23 ± 10.1 mm Hg and mean gradient of 11.9 ± 6.6 mm Hg. Four patients (57.1%) had no demonstrable AR, and mild residual AR was present in the remaining 3 patients (42.9%). Device success according to VARC-2 criteria was achieved in 6 of the 7 patients (85.7%). The patient who did not achieve device success demonstrated an elevated transvalvular gradient (mean, 25 mm Hg; patient #4).

Thirty-day outcomes. At 30-day follow-up, no patient met the VARC-2 defined “early safety” endpoint. Specifically, no patient required further valve-related intervention, or suffered myocardial infarction, stroke, or acute kidney injury stage 2 or 3. There were no deaths during the follow-up period. 

Discussion

We demonstrate that transfemoral implantation of the Lotus TAVI device is safe and feasible for the management of a broad range of degenerate surgical bioprostheses, with successful implantation in all cases without significant residual AR and acceptable transvalvular hemodynamics. 

In recent years, there has been a trend toward a preference for surgical bioprosthetic aortic valve implantation due to associated benefits, including no requirement for formal anticoagulation.⁴ In spite of technological advances with regard to the manufacture of surgical bioprostheses designed to reduce the rate of leaflet degeneration, durability is reported at between 10-20 years.^5-7

The Lotus valve system has been demonstrated to be safe and efficacious for the management of severe calcific native aortic stenosis.^22-24 Conceptually, its application for the treatment of degenerate surgical aortic bioprosthesis (VIV-TAVI) is particularly attractive because it is the only currently commercially available device that is completely repositionable and retrievable. This therefore enables complete valve function evaluation prior to definitive deployment, excluding complications including coronary obstruction^13,14 and suboptimal position with significant residual AR.⁹ 

The majority of experience to date has been with the use of the balloon-expandable Sapien valve (Edwards Lifesciences) and the self-expanding CoreValve (Medtronic),^9,11 which are not repositionable when in their final deployed position. This approach has proven safe and efficacious for this indication in patients deemed to be high risk for redo surgery, and VIV-TAVI is now an accepted management option for this patient group.^9-11 However, in spite of increased operator and institutional experience, complications following VIV-TAVI are not infrequent, with the requirement of a second device implantation required in 5.7% and ostial coronary obstruction in 2% in the Global VIV registry.^9,11 In these instances, the option to retrieve and reposition the valve would be greatly advantageous, and may have reduced the complication rate associated with this intervention. 

In the present case series, we were successful in all 7 consecutive patients treated at our institution. All patients had mild or no residual AR following their VIV procedures. One patient had moderate AR after initial deployment; however, repositioning the valve at a higher implantation rate resulted in mild AR only at final deployment. The transvalvular gradients were also favorable (mean transvalvular peak gradient of 23 ± 10.1 mm Hg and mean gradient of 11.9 ± 6.6 mm Hg) and similar to the postimplantation gradients reported in the Global VIV registry.^9,11 One patient (#4) did demonstrate elevated transvalvular gradients following VIV-TAVI (peak gradient of 40 mm Hg and mean gradient of 25 mm Hg). This patient had a 21 mm Medtronic Freestyle stentless surgical bioprosthesis with mixed degeneration and baseline transvalvular gradients of 64 mm Hg (peak) and 30 mm Hg (mean). We treated this failed bioprosthesis with a 23 mm Lotus device, so it is unlikely that transcatheter bioprosthesis mismatch was the cause,²⁵ although an initial patient-prosthesis mismatch may explain the findings. 

Three of our 7 patients had a PPM in situ prior to VIV-TAVI; of the remaining 4 patients, 1 patient required PPM implantation at day 4 post procedure for complete heart block. The requirement of PPM implantation for conduction disturbances is well recognized following VIV-TAVI;^9,11 however, in view of the relatively small numbers in this series, it is not possible to comment further with regard to whether PPM requirement with the use of the Lotus valve for this indication is different from other valve types.

Finally, no patient in our series suffered coronary obstruction, stroke, myocardial infarction, acute kidney injury (stages 2 or 3) or major vascular complication, indicating acceptable safety of this device for this indication. 

Conclusion

Transfemoral VIV-TAVI for the treatment of surgical aortic bioprosthesis failure with the Lotus device appears to be safe and is associated with no significant residual AR, and offers favorable transvalvular hemodynamics at 30-day follow-up. 

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From the Oxford Heart Centre, John Radcliffe Hospital, Headley Way, Oxford, United Kingdom.

Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Banning reports institutional research grant from Boston Scientific; speaker fees from Abbott Vascular, Medtronic, and Boston Scientific; partially funded by the NIHR Oxford Biomedical Research Centre. Dr Kharbanda reports personal fees from Abbott Vascular, Medtronic, and Boston Scientific; partially funded by the NIHR Oxford Biomedical Research Centre. The remaining authors report no financial relationships or conflicts of interest regarding the content herein.

Manuscript submitted March 4, 2017 and accepted March 24, 2017.

Address for correspondence: Professor Rajesh K. Kharbanda, Oxford Heart Centre, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, United Kingdom. Email: rajesh.kharbanda@ouh.nhs.uk