Two different devices, 1 self-expanding and 1 balloon-expandable, have been developed for patients who underwent transcatheter aortic valve implantation with contrasting data about efficacy and safety. Pubmed, Medline, and Google Scholar were systematically searched for studies of these different devices, with data derived from randomized controlled trial or registries with multivariate analysis. All-cause death at 30 days and at follow-up were the primary end points, whereas postprocedural moderate or severe aortic regurgitation (AR), stroke, major vascular complications, bleedings, and pacemaker implantation the secondary ones. Six studies with 957 self-expanding and 947 balloon-expandable valves were included: 1 randomized controlled trial and 5 observational studies. At 30 days follow-up, rates of death did not differ between self-expanding and balloon-expandable valves (odds ratio [OR] 0.74, 95% confidence interval [CI] 0.47 to 1.17), whereas balloon expandable reduced rates of moderate or severe AR (OR 0.51, 95% CI 0.27 to 0.99) and of pacemaker implantation (OR 0.28, 95% CI 0.17 to 0.47). After a follow-up of 360 days (300 to 390), rates of all-cause death did not differ between the 2 groups. In conclusion, risks of moderate or severe AR and pacemaker implantation were lower with the balloon-expandable devices without an impact on 30 days and midterm mortality.
Transcatheter aortic valve implantation (TAVI) now represents an effective strategy for patients with severe aortic stenosis at high risk for surgery, as demonstrated by randomized controlled trials and large observational studies. Two devices with different technologies have been developed and tested, that is, self-expanding nitinol prosthesis and balloon-expandable metal ones, both of them with excellent results in terms of clinical outcomes. Although self-expanding devices expose patients to more frequent pacemaker implantations, with increased costs but without a negative impact on prognosis, contrasting data have been reported about postimplant aortic regurgitation (AR), one of the most common complications of TAVI, with a well-defined impact on prognosis. Recently, some registries have demonstrated an increased risk of AR for patients treated with self-expanding devices as subsequently confirmed by a single randomized controlled trial. These studies, however, are limited by small sample size, not allowing conclusive appraisal about the most efficacious and safe device for patients with TAVI. Consequently, we performed a meta-analysis of randomized controlled trials and adjusted observational studies to compare self-expanding and balloon-expandable devices.
Methods
The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) amendment to the Quality of Reporting of Meta-analyses statement and recommendations from the Cochrane Collaboration and Meta-analysis of Observational Studies in Epidemiology were followed during the development of the present systematic review.
Pertinent articles were searched for in Medline, Cochrane Library, Biomed Central, and Google Scholar without time limit (up to June 4, 2014) in keeping with established methods with Medical Subject Headings (MeSH) strategy and with the following terms, including “TAVI” or “transcatheter aortic valve implantation” or “self-expandable” or “balloon expandable” or “Corevalve” or “Edwards.”
Two independent reviewers (FDA and GBZ) screened the retrieved citations through the title and/or abstract, and divergences were resolved through consensus. If potentially pertinent, studies were then appraised as complete reports according to the following explicit selection criteria. Studies were included if (i) they reported outcomes of patients with TAVI treated with self-expanding or balloon-expandable techniques and (ii) randomized controlled trials or observational studies adjusted with multivariate analysis, whereas exclusion criteria were (i) nonhuman setting and (ii) duplicate reporting (in which case the manuscript reporting the largest sample of patients was selected).
Two independent reviewers (FDA and GBZ) abstracted the following data on prespecified forms: authors, journal, year of publication, location of the study group, and baseline clinical and interventional features. Data extraction was conducted by mutual agreement, and all potential disagreements were resolved by consensus. All-cause death at 30 days and at follow-up were the primary end points, whereas postprocedure moderate or severe AR, stroke, major vascular complications and bleedings, and pacemaker the secondary ones.
Continuous variables are reported as mean (SD) or median (interquartile). Categorical variables are expressed as n/N (%). Statistical pooling was performed according to a random-effect model with generic inverse-variance weighting, computing risk estimates with 95% confidence intervals, using RevMan 5 (The Cochrane Collaboration, The Nordic Cochrane Centre, Copenhagen, Denmark). Pairwise meta-analysis was performed for overall studies, whereas meta-regression analysis was performed to test the effect of baseline features on primary and secondary outcomes. The study was approved by an institutional review committee and that the subjects gave informed consent.
Results
After literature search, 8 full texts were evaluated for inclusion into review: 2 were excluded as they did not report on outcomes adjusted through multivariate analysis and finally 6 studies were included ( Figure 1 ).
All the studies were multicenter, with a single randomized controlled trial, all of them exploiting balloon-expandable devices of 23 and 26 mm and self-expanding devices of 23, 26, 29, and 31 mm ( Tables 1 and 2 ).
| Include reference | Design of the study | Number of centers | Region | Years of enrollement |
|---|---|---|---|---|
| Abdel-Wahab, 2014 | Observational, prospective | 2 | Europe | 2007-2012 |
| Chieffo, 2013 | Observational, prospective | 3 | Europe | 2011 |
| Choice, 2014 | Randomized controlled | 8 | Europe | 2012-2013 |
| Nombela-Franco, 2013 | Observational, prospective | 4 | North America | 2012-2013 |
| D′Ascenzo, 2013 | Observational, prospective | 5 | Europe | 2008-2012 |
| Watanabe, 2013 | Observational prospective | 2 | Europe | 2008-2012 |
| Study | Kind of balloon expandable devices | Kind of self expandable devices |
|---|---|---|
| Abdel-Wahab, 2014 | Edwards SAPIEN XT 23/26 mm Delivery system of 18/19 F | Medtronic Core Valve 26/29 mm Delivery system of 18 F |
| Chieffo, 2013 | Edwards SAPIEN/ Edwards SAPIEN XT 23/26 mm Delivery system of 18/19/22/24 F | Medtronic Core Valve 26/29 mm Delivery system of 18 F/21 F |
| Choice, 2014 | Edwards SAPIEN XT 23/26/29 mm Delivery system of 16-20 F | Medtronic Core Valve 23/26/29/31 mm Delivery system of 18 F |
| Nombela-Franco, 2013 | Edwards SAPIEN XT 26 mm | Medtronic Core Valve 26 mm |
| D′Ascenzo, 2013 | Edwards SAPIEN/ Edwards SAPIEN XT 23/26/29 mm Delivery system of 19/22/24 F | Medtronic Core Valve 26/29/31 mm Delivery system of 18 F/21 F |
| Watanabe, 2013 | Edwards SAPIEN 23/26 mm Delivery system of 19/22 F | Medtronic Core Valve 26/29 mm Delivery system of 18 F |
Overall, 957 self-expandable and 947 balloon-expandable valves were included, with a median age of 82 (81 to 83) years, 42% (36 to 53) of them being women, with a median logistic EuroSCORE of 22 (21 to 22). Median annulus diameter was 22 mm (21 to 23); 26-mm devices were implanted in 50% (44 to 51) of the patients, 23 mm in 15% (4 to 18), 29 mm in 33% (31 to 37), and 31 mm in 2% (1 to 2) ( Table 3 ).
| 6 studies, 1903 patients | |
|---|---|
| Age (years):mean(range) | 82 (81-83) |
| women | 42% (36%-53%) |
| Diabetes Mellitus | 28% (27%-29%) |
| Previous myocardial infarction | 12% (11%-17%) |
| Ejection fraction less than 35% | 14.5 %(14%-17%) |
| Severe renal disease | 16% (11%-39%) |
| Logistic Euroscore | 22 (21-22) |
| STS score | 8 (7.5-8.5) |
| Annulus (mm) | 22 (21-23) |
| Prosthesis diameter (mm) | |
| 23 | 15 %(4%-18%) |
| 26 | 50%(44%-51%) |
| 29 | 33%(31%-37%) |
| 31 | 2 %(1%-2%) |
At 30 days follow-up, rates of death did not differ between self-expanding and balloon-expandable valves (odds ratio [OR] 0.74, 95% confidence interval [CI] 0.47 to 1.17), whereas balloon expandable reduced rates of moderate or severe AR (OR 0.51, 95% CI 0.27 to 0.99) and of pacemaker implantation (OR 0.28, 95% CI 0.17 to 0.47). Both valves performed similar for major and life-threatening bleedings (24% [16 to 32] vs 27% [20 to 34]; OR 1.40, 95% CI 1.18 to 1.66) and for major vascular complications (6% [3 to 9] vs 9% [5 to 13]; OR 1.17, 95% CI 0.81 to 1.69).
After a follow-up of 360 days (300 to 390), rates of all-cause death did not differ between the 2 groups (15% [11 to 16] vs 13% [12 to 17]; OR 0.95, 95% CI 0.60 to 1.51). At meta-regression analysis, benefit of balloon-expandable valves to reduce AR increased with annulus diameter (beta 0.15, p <0.001; see Figures 2 to 7 ), whereas other clinical variables were not significantly related to primary and secondary end points.
