Citation for published version (APA): Wollersheim, L. W. L. M. (2016). Aortic valve replacement and the stentless Freedom SOLO valve

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1 UvA-DARE (Digital Academic Repository) Aortic valve replacement and the stentless Freedom SOLO valve Wollersheim, Laurens Link to publication Citation for published version (APA): Wollersheim, L. W. L. M. (2016). Aortic valve replacement and the stentless Freedom SOLO valve General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam ( Download date: 22 Apr 2018

2 CHAPTER 3 Aortic valve replacement with the stentless Freedom SOLO bioprosthesis: A systematic review Wollersheim LW, Li WW, Bouma BJ, Repossini A, van der Meulen J, de Mol BA The Annals of Thoracic Surgery 2015;100:

3 34 Chapter 3 ABSTRACT This systematic review examined the clinical and hemodynamic performance of the stentless Freedom SOLO aortic bioprosthesis. The occurrence of postoperative thrombocytopenia was also analyzed. The Freedom SOLO is safe to use in everyday practice with short cross-clamp times, and postoperative pacemaker implantation is notably lower. Valvular gradients are low and remain stable during short-term follow-up. Thrombocytopenia is more severe than in other aortic prostheses; however, this is without clinical consequences. Within a few years, the 15-year follow-up of this bioprosthesis will be known, which will be key to evaluating the long-term durability.

4 Systematic review Freedom SOLO 35 INTRODUCTION American and European guidelines recommend aortic valve replacement (AVR) as the treatment of choice in symptomatic patients with severe aortic valve stenosis [1,2]. Today, 80% of valves implanted at AVR are bioprostheses [3]. Various types of bioprostheses are available, including stented and stentless options. The stentless bioprosthesis was designed to improve hemodynamic performance due to the absence of an obstructing stent [4] and to realize a more physiological flow pattern across the prosthesis than in stented valves [5]. However, the implantation of stentless prostheses was found to be technically more demanding and cross-clamp times were longer [6]. With the introduction of the Freedom SOLO (Sorin Group, Milan, Italy), a modification of the Pericarbon Freedom stentless valve (Sorin Group, Milan, Italy), the technical drawbacks of stentless bioprostheses are diminished [7]. The Freedom SOLO is a pericardial bioprosthesis (Figure 1) and implanted in a supraannular position using one running suture line in the sinuses of Valsalva, thus facilitating easy implantation. The Freedom SOLO valve appears to offer the best of both worlds: it promises the superior hemodynamic performance of a stentless valve combined with a simple and fast implantation technique. In this report, we systematically review the available evidence on the performance of this bioprosthesis regarding clinical outcomes and hemodynamic performance. 3 Figure 1. The stentless Freedom SOLO pericardial bioprosthesis

5 36 Chapter 3 MATERIAL AND METHODS A literature search of MEDLINE, EMBASE and The Cochrane library (Figure 2) was done using the search terms freedom solo or stentless solo. The articles were selected independently by two reviewers (L.W. and W.L.) and are presented in Figure 2. After duplicates were removed, 97 titles were screened. Inclusion criteria for both the title and abstract screening were everything on the Freedom SOLO bioprosthesis. After title screening, 20 titles were excluded (98% agreement). Seventy-seven abstracts were screened and 1 abstract was excluded (99% agreement). Seventy-six full-text articles were assessed for eligibility. There was 96% agreement on full text eligibility, which was resolved after discussion. Four outcome groups were formed clinical outcomes, echocardiography, thrombocytopenia, and other - and each fulltext was assessed for each outcome group. For clinical outcomes, the text had to include number of patients, mortality, and one of the following: reoperation for bleeding, stroke, pacemaker implantation, followup on survival, endocarditis, or reoperations. For echocardiography the text had to include postoperative echocardiography reporting valvular gradients. For thrombocytopenia, the text had to include information on postoperative thrombocytopenia. An addition subgroup was created to examine thrombocytopenia in depth: the text had to include platelet counts both preoperatively and postoperatively and state on which postoperative day. The other category was created to include new information on the Freedom SOLO that did not qualify for the other groups; for example, case reports of valve failures. A total of 35 full-text articles were included in this systematic review [8-42]. Exclusion criteria for the full text analysis can be found in Figure 2. For details on operative technique and figures of the 3 stay sutures and the continuous suture line, we refer to Glauber and colleagues [8]. Figure 2. Flowchart shows article selection for the review

6 Systematic review Freedom SOLO 37 RESULTS Clinical outcomes Table 1 and Table 2 show the clinical outcomes and follow-up of 2185 patients with a Freedom SOLO. In 22 studies, the mean age was 74 years, concomitant procedures were performed in 39% of the patients, and the mean cross-clamp time for isolated AVR with the Freedom SOLO was 66 minutes. Seventy-seven patients (10%) underwent operation for isolated aortic valve insufficiency (AoI). Mean European System for Cardiac Operative Risk Evaluation (EuroSCORE) was 8 and mean logistic EuroSCORE was 12. In all patients, in-hospital and 30-day mortality was 3.5%. The rethoracotomy rate for bleeding was 2.9%, the stroke rate 1.1%, and a permanent pacemaker was implantation in 1.7%. After Freedom SOLO implantation, the reoperation rate was 0.9% (0.5% per patient year), reported over 9 studies (n= 1296) during a mean follow-up of 22 months (maximum 83 months). Five patients underwent reoperation for AoI, 1 patient due to an oversized Freedom SOLO, and 5 patients due to prosthetic valve endocarditis. No patients underwent reoperation due to structural valve deterioration. Overall, prosthetic valve endocarditis was 0.9% (0.5% per patient year), reported over eight studies (n= 1160) during a mean follow-up of 22 months (maximum 83 months). In one study of 13 patients, all of whom were operated on for endocarditis, prosthetic valve endocarditis was absent in 3 to 43 months of follow-up [10]. Overall survival was 91%, 89%, 86%, 78% and 60% at 1, 2, 3, 4 and 5 years, respectively. This was reported in seven, five, five, four and two studies, representing 1147, 818, 818, 690 and 291 patients, respectively. These are the total number of patients in the studies and not the patients at risk at the time of follow-up. 3

7 38 Chapter 3 Table 1 Clinical outcomes author year journal n age concomitant procedures (%) isolated AoI (%) EuroSCORE logistic EuroSCORE XCL time (min) isolated AVR XCL time (min) Glauber Multimed Man Cardiothorac Surg Yerebakan Interact Cardiovasc Thorac Surg Aymard J Thorac Cardiovasc Surg Beholz J Heart Valve Dis Karimov Innovations Kolseth Scand Cardiovasc J Piccardo Ann Thorac Surg Horst J Heart Valve Dis Oses Eur J Cardiothorac Surg Reents J Heart Valve Dis Tarzia Ann Thorac Surg Miceli Eur J Cardiothorac Surg Pfeiffer J Cardiovasc Med 13* Ravenni J Heart Valve Dis Repossini Eur J Cardiothorac Surg Repossini Interact Cardiovasc Thorac Surg Altintas Tex Heart Inst J Iliopoulos J Thorac Cardiovasc Surg Jelenc Heart Surg Forum Pozzoli Ann Thorac Surg Ustunsoy J Heart Valve Dis Thalmann Ann Thorac Surg mortality (%) bleeding (%) stroke (%) pacemaker (%) Total AoI = aortic valve insufficiency, AVR = aortic valve replacement, EuroSCORE = European System for Cardiac Operative Risk Evaluation, CXL = cross-clamp time *all endocarditis patients

8 Systematic review Freedom SOLO 39 Table 2 Clinical follow-up endocarditis (%) 1-y survival (%) 2-y survival (%) 3-y survival (%) 4-y survival (%) 5-y survival (%) reoperation on FS valve (%) author n follow-up* (mon) Aymard maximum Beholz (?-52) Horst (?-56) Oses (2-20) Pfeiffer (3-43) Repossini (0-39) Altintas (24-24) Iliopoulos Ustunsoy (6-69) Thalmann (?-83) Total *follow-up = mean (range) unless stated otherwise, FS = Freedom SOLO 3

9 40 Chapter 3 Hemodynamic performance Tables 3 and 4 report the hemodynamic performance in 1575 patients in 17 studies on the Freedom SOLO. On average, the preoperative peak gradient was 74 mm Hg which declined to 16.8 mm Hg at discharge. During follow-up of 2 to 60 months, the average peak gradient remained stable at 14.6 mm Hg. The average preoperative mean gradient was 47 mm Hg, which declined to 9.1 mm Hg at discharge. During follow-up of 2 to 60 months, the average mean gradient remained stable at 8.6 mm Hg. Seven studies reported on AoI. At discharge, 0.4% of 779 patients had AoI exceeding grade 1, and during follow-up of 4 to 60 months, 0.7% of 923 patients had AoI exceeding grade 1 (combined valvular and paravalvular). Left ventricular ejection fraction remained stable, at 58% preoperatively, 59% at discharge and 61% during follow-up of 2 to 24 months. In five studies (n=441), measurement with transthoracic echocardiography showed left ventricular (LV) mass decreased 19 to 32% up to 2-year follow-up compared with preoperative measurements (p=<0.05) [13-16, 18]. In six studies (n=745), LV end-diastolic diameters decreased 3 to 10% and LV end-systolic diameters decreased 6 to 12% during 1 to 2 years of follow up [15, 16, 18-21]. Only one study showed a high 5% increase in LV end-diastolic diameters and 4% increase in LV end-systolic during 3 months follow-up [17]. Five studies (n=563) reported posterior wall thickness decreased 5 to 14% during 3 to 12 months follow-up [14-17, 19]. Interventricular septum thickness decreased 7 to 15% during 3 to 24 months follow-up in six studies (n=603) [14-19]. Thrombocytopenia Postoperative platelet counts were extracted from 11 studies (n=1015) and compared with their preoperative value [22-32]. A control group was created using postoperative platelet counts from all other aortic valve prostheses included in these 11 studies (n=1090). This comparison is presented in Figure 3. All 11 studies showed that the thrombocytopenia was significantly lower in the Freedom SOLO. In our study, the degree of thrombocytopenia in the Freedom SOLO group was more severe than in the other aortic prostheses. Platelet count after Freedom SOLO implantation was 81% of the preoperative value after 13 days. On average, in the other aortic prostheses platelet counts were back to their preoperative level on postoperative day 9. Of the 11 articles shown in Figure 3, 10 concluded that thrombocytopenia was a numeric phenomenon with no adverse clinical events [22-31]. However, Hirnle and colleagues reported 1 death in 29 Freedom SOLO patients due to thrombotic thrombocytopenic purpura [32]. Seven studies (n=562) reported postoperative thrombocytopenia without reporting the data required for Figure 3 [18-21, 33-35]. Six studies (n=526) reported low platelet count during the first few postoperative days [18-21, 33, 34]. However, no clinical consequences were reported, and the thrombocytopenia was deemed to be a transient laboratory finding. Ustunsoy and colleagues reported platelet transfusion in 6 of 14 patients (43%) [21]. One study reported no difference in postoperative platelet count between the Freedom SOLO and other bio- and mechanical aortic prostheses [35]. In addition, Tarzia and collegues performed a qualitative assessment of platelet function using rotation thromboelastometry and multiple electrode platelet aggregometry. After implantation of the Freedom SOLO, platelet function and platelet interaction with fibrinogen to form thrombus remained normal [33].

10 Systematic review Freedom SOLO 41 Table 3 Hemodynamic performance Pmax Pmean > grade 1 AoI LVEF author year journal n follow-up (mon) pre post latest pre post latest post (%) latest (%) pre post latest Da Col J Heart Valve Dis Glauber Multimed Man Cardiothorac Surg Karaca Anatol J Clin Investig Yerebakan Interact Cardiovasc Thorac Surg Aymard J Thorac Cardiovasc Surg Beholz J Heart Valve Dis Kolseth Scand Cardiovasc J Horst J Heart Valve Dis Oses Eur J Cardiothorac Surg Reents J Heart Valve Dis Repossini Eur J Cardiothorac Surg Repossini Interact Cardiovasc Thorac Surg Altintas Tex Heart Inst J Iliopoulos J Thorac Cardiovasc Surg Jelenc Heart Surg Forum Ustunsoy J Heart Valve Dis Thalmann Ann Thorac Surg Total AoI = aortic insufficiency (AoI >grade 1 is reported), LVEF = left ventricular ejection fraction, post = postoperative, pre = preoperative 3

11 42 Chapter 3 Table 4 Left ventricular remodeling author n Follow-up (mon) LVM (g) LVEDD (mm) LVESD (mm) pre post latest pre post latest pre post latest pre post latest pre post latest Da Col Karaca = = -7 Beholz Repossini Altintas * Iliopoulos = -12 Jelenc * Ustunsoy Thalmann PWT (mm) IVS (mm) IVS = interventricular septum, LVEDD = left ventricular end diastolic diameter, LVESD = left ventricular end systolic diameter, LVM = left ventricular mass, post = postoperative, pre = preoperative, PWT = posterior wall thickness *indexed left ventricular mass

12 Systematic review Freedom SOLO 43 3 Figure 3. Incidence of thrombocytopenia with the Freedom SOLO and other bioprostheses FS = Freedom SOLO, N = number of patients from which the data were extracted, POD = postoperative day Case reports Six case reports described Freedom SOLO failures that needed reintervention. Three patients underwent reoperation [36-38], and 3 patients underwent transcatheter aortic valve implantation [39-41]. During reoperation, Caprili and colleagues found severe calcifications 18 months after the initial AVR [36]. Giordano and colleagues found regurgitation 6 months after the initial AVR due to a rough outflow surface attached to the aortic wall [37]. The final case involved a sudden tear in an otherwise unimpaired prosthesis, 6 years after initial AVR [38]. Learning curve Two studies suggest that the Freedom SOLO has a short learning curve, which is illustrated by decreasing cross-clamp times. Beholz and colleagues showed that after 10 cases, the mean cross-clamp time decreased from 46 minutes to 36 minutes for the next 38 cases [42]. Thalmann and colleagues showed a decreased cross-clamp time of 17% after the first 10 cases by each of 3 surgeons. Another reduction of 15% was achieved after the next 10 cases [20]. COMMENT This systematic review shows that AVR with the Freedom SOLO is safe and feasible, with good prosthesis performance after a mean follow-up of 22 months (maximum 83 months). Operative mortality of 3.5% and stroke rate of 1.1% in 2185 patients with 39% concomitant procedures is comparable with other studies.

13 44 Chapter 3 Data from the Society of Thoracic Surgeons National Database shows an observed mortality of 3.0% and stroke in 1.5% in isolated AVRs [3]. The Freedom SOLO shows excellent outcomes regarding the need for postoperative pacemaker implantation. Seven studies that included 702 patients with 49% concomitant procedures reported a pacemaker implantation rate of only 1.7%. In comparison, the reported incidence of pacemaker implantation after isolated AVR is 3.2% to 4% [3, 43] and in series with concomitant procedures 6.6% to 7.2% [44, 45]. We hypothesize this lower incidence in the Freedom SOLO is due to its supraannular implantation technique. The sutures are further away from the conduction system compared with stented prostheses, which necessitate sutures in the native aortic annulus. The Freedom SOLO prosthesis has a simple and fast implantation technique with a short learning curve. In our review, cross-clamp time for isolated AVR was 66 minutes, approximating cross-clamp times of stented aortic bioprostheses (50 to 67 minutes) [46, 47]. This is shorter than other stentless aortic bioprostheses (72 to 128 minutes) [48, 49]. Long-term durability remains an essential feature for aortic bioprostheses. Our review reports 0.5% reoperation rate per patient-year for the Freedom SOLO measured during a mean follow-up of 22 months. In comparison, the reoperation rate for stented aortic bioprostheses is % after 5 years [50, 51] and 10% after 10 years [52]. Although none of the case series report early structural valve deterioration of the Freedom SOLO, this follow-up period is not yet long enough to be able to draw firm conclusions regarding durability. Longer follow-up will reveal if the Freedom SOLO is a durable prosthesis. Six case reports described Freedom SOLO failures requiring high-risk reintervention. In 3 of these patients, a transcatheter approach was used, and the distance between the coronary ostia and the supra-annular Freedom SOLO was emphasized in all cases. Remarkably, a different transcatheter prosthesis was used in all interventions and none were shown of obstruct the coronary ostia. In case of bioprosthesis failure requiring a transcatheter approach, a potential advantage for stentless bioprosthesis could be the larger internal diameter of the stentless bioprosthesis compared to a stented bioprosthesis due to the absence of a stent. Therefore, a larger transcatheter bioprosthesis could be implanted [53]. Prosthetic valve endocarditis occurs in 1% to 6% of patients, with an incidence of 0.3% to 1.2% per patientyear [54]. The incidence of prosthetic valve endocarditis of 0.5% per patient-year in the Freedom SOLO is comparable, also in patients who underwent operation for endocarditis. This could be due to the minimal amount of foreign body material associated with the Freedom SOLO (ie, the lack of a stent and the absence of pledgeted sutures). Overall survival is similar to reports in the literature. In a population of the same mean age of 74 years, survival was 90 to 93% at 1 year, 85% at 3 years, and 77 to 80% at 5 years after AVR with various aortic bioprostheses [50, 51]. The 5-year survival appears to be lower; however, this could be due to the few Freedom SOLO patients at risk at 5 years of follow-up. The effective orifice area of the Freedom SOLO is maximized because of the stentless design. This leads to low peak and mean valvular gradients that remain stable during follow-up. In comparison, stented aortic bioprostheses have higher peak gradients of 20 to 30 mmhg and mean gradients of 10 to 16 mmhg [47]. Owing to the implantation technique, paravalvular leakage also appears to be low. Remodeling of the LV

14 Systematic review Freedom SOLO 45 has also been shown, with a reduction of LV mass, LV end-diastolic diameters, LV end-systolic diameters, posterior wall thickness, and interventricular septum thickness. Because of the increased risk of sudden cardiac death associated with LV hypertrophy, a decrease in these parameters is desirable [55]. Postoperative thrombocytopenia has been reported after Freedom SOLO implantation and seems to be more evident than in other prostheses, but appears to be a transient laboratory finding. Only one significant complication was observed in 1577 patients; therefore, the clinical significance of this remarkable laboratory finding remains to be clarified. The Freedom SOLO is detoxified with homocysteic acid and stored in a neutral, aldehyde-free solution. That the homocysteic acid could be responsible for the thrombocytopenia has been suggested [28]; however, this hypothesis was rejected because studies of another bioprosthesis detoxified with the same solution did not reveal comparable thrombocytopenia [56], and rinsing the Freedom SOLO before implantation did not prevent thrombocytopenia [24]. Another hypothesis, that the thrombocytopenia was due to the different implantation technique, was also rejected [27]. O Brien previously used this technique with another bioprosthesis, and thrombocytopenia did not result [4]. Still, the cause of the transient thrombocytopenia remains to be elucidated. 3 Limitations This systematic review has several limitations. None of the studies was randomized, and only six prospective studies were included [9, 14-18]. The other studies are retrospective and therefore subject to methodological limitations. Seven out of 22 studies [13, 23-26, 28, 31] that reported clinical outcomes had a control group. Selection bias was present in almost all studies because the choice of prosthesis was based on the surgeon s preference. Publication bias could also be present; for example, only seven out of 17 papers that reported hemodynamic data presented their findings on AoI. In addition, the follow-up is too short to draw conclusions on the durability of the Freedom SOLO. Substantial longer follow-up is necessary. CONCLUSION The Freedom SOLO is a stentless aortic bioprosthesis that is safe to use in everyday practice, with crossclamp times comparable to those of stented bioprostheses. Postoperative pacemaker implantation is notably lower, the learning curve is short, and the incidence of prosthetic valve endocarditis is comparable with other prostheses. Valvular gradients are low and remained stable during short-term follow-up. Postoperative thrombocytopenia appears to be a transient laboratory finding, although the cause of this phenomenon is not known. Within a few years, the 15-year follow-up will be available, which will be key to judging the true durability of this bioprosthesis. Thus far, the stentless Freedom SOLO seems to offer the best of both worlds, with superior hemodynamic performance and short cross-clamp times.

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