Initial Single-Center Experience With the Fully Repositionable Transfemoral Lotus Aortic Valve System

Abstract: Background. Transcatheter aortic valve replacement (TAVR) has become the standard therapy for patients with severe symptomatic aortic stenosis and unacceptable high risk for surgical aortic valve replacement. Several different devices for TAVR have been introduced so far, each of them with unique features. Aims. To analyze our first real-world experience with the second-generation, mechanically expanded, fully repositionable transfemoral Lotus TAVR device (Boston Scientific). Results. Between August 2014 and January 2016, a total of 298 patients were scheduled for transfemoral TAVR at our institution. Among them, 145 patients received a CoreValve/CoreValve Evolut R device (Medtronic), 90 patients received a Sapien 3 device (Edwards Lifesciences), and 63 patients were scheduled for Lotus TAVR device implantation based on access vessel size and annulus diameter. Of the 63 subsequent patients scheduled, 62 were successfully implanted. Short-term Valve Academic Research Consortium (VARC)-2 results at 30 days showed a 6.4% all-cause mortality, a 3.2% major stroke rate, a 36.5% new permanent pacemaker rate and 1.6% major vascular complications. Of note was the near absence of significant residual aortic regurgitation in the presence of a favorable hemodynamic profile even in patients with difficult anatomy. Conclusion. Our first real-time experience with the fully repositionable Lotus TAVR system mimics the results of early clinical studies like REPRISE II. Further next-generation modifications in combination with gaining experience with this new device will likely reduce the need for new permanent pacemaker implantation and vascular complications in the future. 

J INVASIVE CARDIOL 2017;29(1):30-35. Epub 2016 November 15.

Key words: TAVR, Lotus, transfemoral, outcomes

Transcatheter aortic valve replacement (TAVR) has become the standard treatment for patients with severe symptomatic aortic stenosis, who are at high risk for surgical aortic valve replacement (SAVR). Currently, several new TAVR prosthesis types have been introduced or are currently studied in the clinical setting. Among all types of prostheses, the balloon-expandable Sapien prostheses (XT or Sapien 3; Edwards Lifesciences) and the Core-Valve (Medtronic) prosthesis are by far the best studied.^1-5 The PARTNER 1 trials, as well as the US CoreValve Pivotal trials, have demonstrated the superiority of TAVR vs conservative treatment in inoperable patients with severe aortic stenosis and non-inferiority (PARTNER 1) or superiority (US CoreValve Pivotal) for TAVR vs SAVR in high-risk patients. Nevertheless, the technique is still hampered by the risk of insufficient procedural results with subsequent significant aortic regurgitation or need for pacemaker implantation.^6-8 With the latest generation of devices, some of these disadvantages have been addressed by technical modifications like paravalvular sealing features, repositionable devices, and implantation techniques.^9-11

The transfemoral Lotus TAVR device (Boston Scientific) differs from other devices because it is fully repositionable (complete reversibility after full deployment of the valve) and has a paravalvular sealing skirt in order to reduce postinterventional aortic regurgitation (Figure 1).¹⁰ Initial experience with this second-generation device has accordingly demonstrated low rates of postinterventional aortic regurgitation but concomitantly relatively high rates of permanent pacemaker implantation. The valve itself is deployed via an 18 Fr or 20 Fr preshaped transfemoral system (for the 23 mm and 25 mm/27 mm Lotus devices, respectively). The REPRISE I and II studies have demonstrated excellent preliminary results.^12,13 However, real-world experience may differ from early studies due to selection bias and learning curve in the early stages of device experience. Thus, real-world data are necessary to confirm results of early trials, especially in patients with unfavorable anatomy.

We provide herein a retrospective analysis of our first real-world experience with this new device, as well as procedural results and short-term outcomes, in the first consecutive 63 patients scheduled for Lotus implantation at our institution between August 2014 and January 2016.

Methods

Study population. Between August 2014 and January 2016, a total of 298 patients were scheduled for transfemoral TAVR and were subsequently implanted at our institution with one of the following devices: Sapien 3 (Edwards Lifesciences; n = 90), CoreValve (Medtronic; n = 36), the CoreValve Evolut R (Medtronic; n = 109), or the Lotus device (Boston Scientific; n = 63). Since the Lotus device was newly introduced, we analyzed all 63 subsequent patients implanted with this device after the initial proctoring phase (n = 5). The decision regarding whether patients were scheduled for TAVR or SAVR was made by the heart team at our institution. The decision regarding the valve type used was at the operator’s discretion. 

Transfemoral Lotus implantation and follow-up. Briefly, aortic valve implantations with the Lotus device were performed after placing two ProGlide SH access-site closure devices (Abbott Vascular) and a transjugular pacemaker. Preparatory balloon valvuloplasty was performed according to the operator’s discretion. All procedures were performed under local anesthesia and conscious sedation, monitored by a cardiac anesthesiologist. Procedural results and 30-day outcomes of the patients were assessed according to the Valve Academic Research Consortium (VARC)-2 criteria.¹⁴ Patient characteristics were collected with respect to age, gender, STS score, aortic valve area (AVA), comorbidities, etc. The study reported here was in accordance with the ethics committee of the Heidelberg University Hospital.

Computed tomography for patient selection for the Lotus device. All scans were performed using a 256-slice Brilliance iCT scanner (Philips Healthcare). For assessment of aortic valvular structures, systolic images (40% of the cardiac cycle) were used. Annulus size was determined by calculation of the three-dimensional (3D) area-derived annular diameter (in mm). Determination of the annular dimensions was performed by first defining the annular plane as described.¹⁵ Sizing recommendations for the Lotus device are as follows: the 23 mm device fits annulus sizes ≥19 mm to ≤23 mm, the 25 mm device fits annulus sizes >23 mm to ≤25 mm, and the 27 mm device fits annulus sizes >25 mm to ≤27 mm, all based on area-derived annular diameter. Minimal access vessel size was determined by scrolling through the aorta and pelvic vessels down to the femoral bifurcation with continuous determination of vessel size. Transfemoral access sheaths for the Lotus device are 18 Fr for the 23 mm device and 20 Fr for the 25 mm and 27 mm devices. Thus, only patients with at least 6 mm minimal access vessel diameter (for the 23 mm device) and 6.5 mm minimal access vessel size (for the 25 and 27 mm devices) were considered suitable for transfemoral Lotus valve implantation.

Statistical analysis. Statistical analyses were performed with MedCalc Version 11.6.0 for Windows (MedCalc Software). Data are shown as mean ± standard deviation or numbers. Logistic regression was used to analyze variables associated with pacemaker implantation. The Chi² test was used for comparison of categorical variables and the t-test for continuous variables, once normality was achieved by log transformation where necessary. A P-value <.05 was considered statistically significant.

Results

Patient characteristics. Between August 2014 (when the Lotus device was introduced at our institution) and January 2016, a total of 63 out of 298 patients were scheduled for transfemoral Lotus TAVR implantation at our center. During the same period, 36 CoreValve, 109 CoreValve Evolut R, and 90 Edwards Sapien 3 devices were implanted. The decision regarding whether a patient could be selected for Lotus device implantation was based on access vessel size in combination with annulus diameter. Characteristics of all patients scheduled for Lotus implantation compared with all other patients are shown in Table 1. Mean patient age was 81.3 years and mean STS score was 5.6%. Underlying aortic valve anatomy was tricuspid in 61 patients and bicuspid in 2 patients. Severe calcification (including outflow tract calcification) was present in 28 cases (44.4%). The annular-horizontal plane deviation was ≥60° in 13 patients (20.6%) and ≥65° in 4 patients (6.3%). Preexisting right bundle-branch block was present in 10 patients (15.9%), whereas 6 patients (9.5%) had preexisting pacemakers. 

Procedural results. Among the 63 patients scheduled for Lotus device implantation after the initial proctoring phase, 62 were successfully implanted according to VARC-2 criteria. One patient developed an iliac artery perforation before the Lotus device was inserted and died. Predilation was used in 28 of the successfully implanted patients (45.2%), whereas the device was implanted without predilation in the remaining cases. No patient had to be postdilated. Repositioning at least once during the procedure was necessary in 18 patients (28.6%); in 6 of these patients, repositioning was necessary at least twice (9.5%). The 27 mm Lotus valve was by far the most often implanted device (50%), whereas the 25 mm and 23 mm devices were less frequently used (27.4% and 22.6%, respectively). No case of coronary occlusion occurred. Procedural results compared with all other patients are shown in Table 2. 

Short-term VARC-2 results (Table 3). All-cause mortality at 30 days post TAVR was 6.3%, major/fatal stroke rate was 3.2%, and permanent pacemaker rate was 36.5%. Among the 4 patients who died, 1 patient who suffered from severe chronic obstructive pulmonary disease died of respiratory decompensation, 1 patient died of hemorrhagic stroke, 1 patient died a few days after a periprocedural major stroke had occurred, and 1 patient died after iliac artery perforation due to fatal vascular complication. One major access-site related complication was observed (see above). Minor access-site related complications were observed more frequently in 14 patients and were mainly due to hematoma formation, whereas stent-graft implantations were rare (n = 2).

Among the 23 patients who received a postinterventional pacemaker after TAVR were 17 patients with atrioventricular (AV) block III; 3 patients with AV block II type 2; 1 patient with imminent trifascicular block; 1 patient with bradycardia-tachycardia syndrome; and 1 patient with postinterventional left bundle-branch block and progressive AV block type 1 with bradycardia. Of all patients who underwent Lotus valve implantation, a total of 26 patients subsequently developed a left bundle-branch block. The frequencies of device-related postprocedural significant conduction disturbances are shown in Table 4.

Neither the eccentricity index of the valve (eccentricity index = 1 – D_min/D_max), the degree of valve oversizing (ratio of valve diameter to area-derived annular diameter), nor the depth of implantation turned out to be predictive for postinterventional need for permanent pacemaker implantation. However, preexisting right bundle-branch block was a strong predictor for the postinterventional need for permanent pacemaker implantation (odds ratio, 5.396; 95% confidence interval, 1.2354-23.5665; P=.02). When compared with patients who were implanted with other devices, more of the Lotus patients had preexisting right bundle-branch block (Lotus 17.5% vs Sapien 3 13.3% vs CoreValve/Evolut R 9.7%).

The Lotus device in specific patient subsets with difficult anatomy. Several anatomical conditions have been related to suboptimal results after TAVR implantation. Among them are a nearly horizontal aorta, significant outflow tract calcifications, or bicuspid valves.^16-18 In 13 of our patients, the angle between the annular plane and the horizontal plane was ≥60° and in 4 of the patients it was >65°. Again, significant (more than mild) postinterventional aortic regurgitation was not observed in any of these patients (Figure 2A). Significant left ventricular outflow tract calcifications were present in 11 Lotus cohort patients. More than mild postinterventional aortic regurgitation was not present in any of these 11 patients (Figure 2B). Finally, 2 patients with true bicuspid aortic valve anatomy were implanted with the Lotus device in our series with excellent postinterventional results (Figure 2C). 

Discussion

The mechanically expanded, fully repositionable transfemoral Lotus device has been recently introduced into real-world practice. Preliminary studies like the REPRISE trials have shown promising results.^12,13 Here, we report our first single-center real-world experience with this device in 63 patients and include VARC-2 defined short-term outcomes. The device proved to give excellent results with respect to postinterventional aortic regurgitation, a pacemaker rate of roughly one-third, and a reasonable safety profile. In patients with difficult anatomy prone to device malfunction like horizontal aorta, bicuspid anatomy, or outflow tract calcification, procedural results were similar, especially with respect to postinterventional aortic regurgitation. 

Since the implementation of the TAVR procedure in daily routine, many devices have been evaluated in early clinical studies and introduced into real-world practice. Among them, the Edwards Sapien 3 and the CoreValve Evolut R represent two types of third-generation devices with improved abilities to reduce paravalvular regurgitation, pacemaker rate, and ease of implantation.^9,19 Their preceding valve designs (the CoreValve and Sapien XT) have already demonstrated excellent results in large-scale clinical studies in comparison with the conservative approach as well as the surgical approach in high-risk patients with symptomatic severe aortic stenosis.^1-5 The Lotus device adds two new features to the TAVR device landscape. First, it is a fully repositionable device, which means that complete deployment and assessment of device success is possible prior to release of the device. Second, it includes a paravalvular sealing feature (adaptive seal) that should help to achieve device success even in patients with heavy calcification in the absence of the risk of annular rupture due to aggressive postdilation. Both features make the Lotus device particularly useful in the setting of difficult anatomies like horizontal aorta, outflow tract calcification, or bicuspid valve, which are all prone to device malfunction, especially with self-expanding valves.^16-18 In our cohort, such anatomic conditions were present in one-third of the patients. However, results with respect to postprocedural aortic regurgitation were equally excellent when compared with patients who had less difficult anatomies. Of note, repositioning of the device at least once during the procedure was necessary in more than one-fourth of the patients, indicating the value of this feature to achieve optimal hemodynamic results.

In our study, we also found a permanent pacemaker implantation rate of 36%. At first sight, this is quite high compared with other devices. Recent studies using the Edwards Sapien 3 and CoreValve Evolut R devices have demonstrated pacemaker rates between 4%-17%.^9,19-21 The reasons for this higher number of pacemakers needed after implantation of the Lotus device may be related to several aspects. First, the device has a very high radial strength and a high density of metal in its frame, which both may have added to increased pressure on the conduction system. Second, due to the relatively low real-world experience with this device, implantation techniques aiming for a reduction of pacemaker rates have not been developed yet. High implantations have been shown to reduce pacemaker rates for both balloon-expanding and self-expanding TAVR devices in the past.^11,22 Thus, increased experience with the device may further reduce the number of pacemaker implants. Finally, the deployment of the device in its current form takes place to a significant degree in the outflow tract of the left ventricle. Therefore, temporary affections of the left bundle branch may also lead to preliminary pacemaker insertion without the need for long-term pacing. Again, data like the amount of paced beats during follow-up are still lacking with this device. In addition, future changes in the release pattern of the device may thus further reduce the need for postprocedural pacing. 

Peripheral complications during transfemoral TAVR procedures have clearly been related to short-term mortality in this often old and fragile patient population.^23-26 There was a relatively high number of vascular access-site complications (mostly hematomas), with 1 fatal outcome in our cohort. This was probably mainly attributable to the fact that a 27 mm device was chosen in about one-half of the patients, which necessitated a 20 Fr access sheath for device application. As with other devices, the future reduction of the access sheath sizes for the Lotus device will reduce the number of access-site complications.²⁷

Study limitations. The major limitation of our study is the still relatively small number of patients and therefore the lack of statistical power to sufficiently analyze predictors for permanent pacemaker implantation. In addition, the decision about which type of TAVR device was used in a given patient was based on the operator’s discretion, making some sort of selection bias likely. Therefore, one should be careful in a head-to-head comparison between the different devices used in our manuscript. As demonstrated in Table 1, there are significant differences between the groups. For instance, patients treated with the Lotus or Sapien 3 device were much more likely to have heavily calcified annuli (and were therefore at an increased risk for significant postinterventional leakage), making a paravalvular seal/skirt (like in the Sapien 3 and Lotus devices) particularly useful. Nevertheless, the procedural and 30-day outcomes reported in our study, even in the patients with difficult anatomies, are very similar to the numbers of the few existing trials with the Lotus device reported to date, thus confirming the strengths and weaknesses of the current version of this device.

Conclusion

The transfemoral Lotus TAVR device has unique features that result in a very low rate of paravalvular leakage even in difficult anatomies. This first real-time experience already shows excellent results, and future modifications (eg, access sheath size) along with gains in operator experience and improvements in implantation techniques will further improve the performance of the next generation of this device.

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From the Department of Cardiology, Angiology & Pulmology, Heidelberg University Hospital, Heidelberg, Germany.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted May 11, 2016, provisional acceptance given June 3, 2016, final version accepted August 5, 2016.

Address for correspondence: Emmanuel Chorianopoulos, MD, Department of Cardiology, Angiology & Pulmology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany. Email: e.chorianopoulos@med.uni-heidelberg.de