Discussion
This study presents the first examination of cost data on sutureless, rapid deployment valves in the United States. Like many studies we showed shorter cardiopulmonary bypass and aortic cross clamp times with good outcomes. Also shown was an initially high permanent pacemaker rate that declined over time. Hospital costs between SLV and standard sutured valves were not different.
Overall, outcomes with SLV have been good. The Europeans have a longer and more extensive experience. In reviewing that literature the early reports in isolated AVR were encouraging, showing safety and good hemodynamic results.4,5 In the Cavalier Trial,17 Perceval valves were placed in 628 patients in several European centers from 2010 to 2013 with a mean cross-clamp time of 32 minutes and post-operative mean gradient of about 10 mmHg. Thirty day overall and valve-related mortality rates were 3.7% and 0.5%, respectively. The valve explant rate was 0.6%, and stroke rate was 2.1%. Five year data were presented by Shrestha, et al. in 2016 and showed similar short-term outcomes in 731 patients undergoing AVR from 2007 to 2012.18 There was a 1% incidence of late major paravalvular leak. Early mortality was about 2%, 1 year 8% and 5 year was 25%. The average mean gradient at 5 years was 7.8 mmHg.
The post-operative mean gradients reported in studies of rapid deployment valves are interesting and may suggest a learning curve. When an oversized SLV is placed the mean gradient may be elevated due to decreased leaflet excursion. In a large German registry review of over 20,000 patients undergoing isolated SAVR three rapid deployment valves were compared. The Perceval valve was less likely to be a smaller sized valve (≤ 21 mm) (Perceval 10% of patients, balloon expandable INTUITY valve (Edwards Lifesciences, Irvine, California) 25%, and self-expanding, nitinol-based 3F Enable valve (Medtronic, Dublin, Ireland) 27%; P<.001). The median postoperative mean aortic valve gradient was highest in the Perceval (14 mmHg, INTUITY 9 mmHg and Enable 10 mmHg; P<.001), and permanent pacemaker was highest with Perceval (11%, INTUITY 7% and Enable 7%; P<.02). It is common for surgeons to place the largest valve possible, but right-sizing of this valve allows for optimal hemodynamics and avoidance of permanent pacemaker. Subsequent studies have shown the PPM rate can be reduced by changes in implantation technique.19
Comparisons have been made to stented surgical valves and transcatheter aortic valve replacements (TAVR). A 2014 study compared Perceval to Carpentier-Edwards Perimount aortic prostheses showing lower CPB and cross-clamp times with SLV.20 The post-operative peak gradients were lower with SLV, but the average mean gradients were not different in similarly sized valves (approximately 23 mm for both groups). There was no difference in PPM in this small study. A 2015 study from France compared hemodynamic performance of small Perceval prostheses in elderly patients with larger size Perceval valves and found no difference in post-operative mean gradient (10.3 mmHg for small valves and 11.3 mmHg for medium and large valves; P=.20), indexed effective orifice area (0.84 cm2/m2for small and 0.86 ; P=.76) or presence of patient prosthesis mismatch (absent in 45% v. 43%, moderate in 45% v. 39% and severe in 10% v. 20%; P=0.6). At a median follow up of 1.5 years the echo measurements and survival did not differ. This suggests that a stentless valve in the small aortic root can provide good hemodynamics.21
Recently published industry sponsored clinical trials in low-risk patients with severe aortic stenosis have shown that transcatheter aortic valve replacement (TAVR) is at least comparable in short term outcomes when compared to surgical aortic valve replacement.22,23In both trials TAVR resulted in less stroke, bleeding, atrial fibrillation and shorter length of stay with similar valve performance at one year. The type of surgical valve used in these trials was left to the surgeon, and it is not clear if certain prostheses have any advantage. There have been no randomized control trials comparing sutureless valves to date. Several retrospective studies comparing older TAVR technology showed some advantages to SAVR with sutureless valves (lower rates of vascular complications, paravalvular leak, permanent pacemaker, and renal failure) which have been largely mitigated with advancements in TAVR technology. Interestingly, two studies with mid-term patient matched outcome data showed no difference in survival at one year, but a survival advantage for Perceval at two years; 97.3% vs. 86.5%, P = .015 and 94.9% vs. 79.5%, P = .02.24,25There is great interest in understanding how TAVR will compare with SAVR in mid- and long-term outcomes. Similar to our findings, a number of studies have demonstrated that sutureless valve technology facilitates minimally invasive approaches. The Sutureless and Rapid Deployment International Registry published results of 1935 patients undergoing SAVR with sutureless and rapid deployment valves and showed 73% were implanted in a minimally invasive fashion.26 In contrast, overall use of mini approaches to SAVR have been reported to be 15% in the United States, 12% in the United Kingdom and 25% in Germany.27 It is clear that for SAVR to compete surgeons should work to improve outcomes and utilize minimally invasive approaches for patients who are not currently candidates for transcatheter technology.
There have been concerns raised about possible complications associated with sutureless valve technology. There have been reports of paravalvular leak, especially in the early experience.28 The cause of paravalvular leak is often due to incorrect sizing of the valve. There is certainly a learning curve associated with new valve technology and ensuring proper sizing is important. It has been the practice of our group to not accept more than trace paravalvular leak on the intraoperative post implant echocardiogram. Thrombocytopenia has also been described. In one study the average platelet count at discharge after Perceval implantation was 102,000 ± 28,000 which was significantly lower than Edwards Intuity rapid deployment valve.29 Another study compared Perceval (n= 72 patients) to Perimount Magna Ease (n=101 patients) and showed a greater maximum drop in platelet count at a mean of post-operative day 2.3 (58% in Perceval vs. 44% in Magna Ease; P=.0001), less likely recovery to pre-operative levels by discharge (26% in Perceval and 44% in Magna Ease; P=.018), and more red blood cell (P=.007) and platelet (P=.009) transfusion with Perceval. We did not appreciate a significant difference in bleeding rates or transfusion, and often treated the thrombocytopenia expectantly if there were no bleeding complications. Migration is extremely rare, but has been reported.30 Two clinical situations have been described. The first is in double, aortic and mitral, valve replacement where the two prostheses interact and the sutureless valve becomes unstable. There appears to be potentially predictive factors including a short aorticomitral curtain (<6 mm) and the angle of the aorta and mitral annuli. These factors are currently being studied. The second is infective endocarditis after sutureless valve placement. If there is a large annular abscess the valve may become unstable, and at risk of migration. Our experience with a single case has suggested that early surgery in these cases may be beneficial. Durability of the valve is being studied as well. It has been shown in the European literature that the 5-year durability data is reasonable. In a 2016 multicenter paper, Shrestha et al.18 showed a late (more than 30 days after implant) explant rate of 1.5%, major paravalvular leak rate of 1%, endocarditis 1.6% and AV block in 1.4%. At the 2019 American Association for Thoracic Surgery annual meeting Dr. Meuris presented 11-year data on 486 consecutive patients at Leuven University Hospital. In their series there were no explants for structural valve degeneration. The manuscript and additional long-term data are pending. In our current series no valves have been explanted for structural valve degeneration. However, It does appear that sutureless valves will offer a good platform for future valve in valve TAVR as it is essentially a stentless valve.31 For a small Perceval valve a 23 mm Edwards S3 TAVR valve can be considered.
There are economic considerations when using new technology, and date there have been no data on cost in the United States for this procedure. Sutureless and rapid deployment valves often cost more than standard aortic prostheses. At our institution, during the study period, the Perceval valve cost approximately $5,670 more than sutured valves. A study from Germany showed use of sutureless valves resulted in lower cost based on savings in diagnostics and hospital length of stay.32 In our current study we found that a higher pacemaker rate incurred extra cost. There have been excellent descriptions of techniques to reduce pacemaker rate33, and our group has been able to continue decreasing the need to post-operative permanent pacemakers.