Open Issues in TAVI Part 2
Open Issues in TAVI Part 2
Although randomized clinical trials are the foundation to establish evidence-based guidance in patient management, observational studies serve an important complementary role by evaluating novel therapies in routine clinical practice, investigating more complex and diverse patient populations excluded from (or under-represented in) randomized trials (renal failure, atrial fibrillation, and peripheral vascular disease).
Both nation-wide registries and valve-specific registries have been reported. Data from these registries confirmed that TAVI improved survival compared with medical treatment alone in patients encountered in routine clinical practice. Moreover, safety and efficacy were comparable with randomized trials with acceptable complication rates confirming that TAVI is a reasonable treatment option in high-risk patients. This was recently confirmed by a multicentre trial randomizing 390 high-risk patients to TAVI (STS-PROM 7.3 ± 3.0%) and 357 to SAVR (STS-PROM 7.5 ± 3.4%). Transcatheter aortic valve implantation was associated with a lower mortality rate at 1-year follow-up when compared with SAVR (14.2 vs. 19.1%) representing an absolute risk reduction of 4.9%. Importantly, improved outcomes over time highlighted the learning curve experience as a result of improved patient selection and implantation techniques. More recently, several registries pointed to the inclusion of lower-risk patients with a parallel decrease in peri-procedural complications, indicating a change in practice as a result of ongoing improvements in a device design. The registries also allowed to unveil important improvements in the outcome such as the decrease in vascular complications due to small-sized delivery catheters. Moreover, registries were instrumental to establish TAV-in-SAV implantation as a valuable alternative to redo-operations in patients with failed surgical bioprostheses with important insights as it relates to device selection. Finally, TAVI implantation data from 11 countries including Germany, France, Italy, UK, Spain, the Netherlands, Switzerland, Belgium, Portugal, Denmark, and Ireland between 2007 and 2011 allowed to describe the adoption of this technology across Europe and highlighted important variations related to economic indices and healthcare reimbursement scheme.
To comprehensively define the therapeutic role of TAVI in clinical practice, data from conventional SAVR are desirable as a comparator. However, the patient cohorts undergoing SAVR or TAVI are so different in many critical variables that the statistical analysis of these registries reaches its limits. In the GARY registry, the measured outcome was compared with the outcome results as predicted by the German Aortic Valve (AV) Score. By using this score in TAVI patients treated in 2011, the expected mortality for the highest risk quartile (>6% expected in hospital) was 18.6%, but actually amounted to only 16.8%. In parallel, in the highest risk quartile of patients undergoing SAVR, the observed mortality was 9% instead of 17%. These findings highlight that TAVI was at least as good as SAVR in high-risk patients. However, there have also been a considerable number of patients with low-estimated risk undergoing TAVI. This is not necessarily due to inappropriate indications, but may reflect the limitation of the scores (as discussed in the paragraph on risk scores, see Part 1).
Lessons From Transcatheter Aortic Valve Implantation Registries: Results in Clinical Practice
Although randomized clinical trials are the foundation to establish evidence-based guidance in patient management, observational studies serve an important complementary role by evaluating novel therapies in routine clinical practice, investigating more complex and diverse patient populations excluded from (or under-represented in) randomized trials (renal failure, atrial fibrillation, and peripheral vascular disease).
Both nation-wide registries and valve-specific registries have been reported. Data from these registries confirmed that TAVI improved survival compared with medical treatment alone in patients encountered in routine clinical practice. Moreover, safety and efficacy were comparable with randomized trials with acceptable complication rates confirming that TAVI is a reasonable treatment option in high-risk patients. This was recently confirmed by a multicentre trial randomizing 390 high-risk patients to TAVI (STS-PROM 7.3 ± 3.0%) and 357 to SAVR (STS-PROM 7.5 ± 3.4%). Transcatheter aortic valve implantation was associated with a lower mortality rate at 1-year follow-up when compared with SAVR (14.2 vs. 19.1%) representing an absolute risk reduction of 4.9%. Importantly, improved outcomes over time highlighted the learning curve experience as a result of improved patient selection and implantation techniques. More recently, several registries pointed to the inclusion of lower-risk patients with a parallel decrease in peri-procedural complications, indicating a change in practice as a result of ongoing improvements in a device design. The registries also allowed to unveil important improvements in the outcome such as the decrease in vascular complications due to small-sized delivery catheters. Moreover, registries were instrumental to establish TAV-in-SAV implantation as a valuable alternative to redo-operations in patients with failed surgical bioprostheses with important insights as it relates to device selection. Finally, TAVI implantation data from 11 countries including Germany, France, Italy, UK, Spain, the Netherlands, Switzerland, Belgium, Portugal, Denmark, and Ireland between 2007 and 2011 allowed to describe the adoption of this technology across Europe and highlighted important variations related to economic indices and healthcare reimbursement scheme.
To comprehensively define the therapeutic role of TAVI in clinical practice, data from conventional SAVR are desirable as a comparator. However, the patient cohorts undergoing SAVR or TAVI are so different in many critical variables that the statistical analysis of these registries reaches its limits. In the GARY registry, the measured outcome was compared with the outcome results as predicted by the German Aortic Valve (AV) Score. By using this score in TAVI patients treated in 2011, the expected mortality for the highest risk quartile (>6% expected in hospital) was 18.6%, but actually amounted to only 16.8%. In parallel, in the highest risk quartile of patients undergoing SAVR, the observed mortality was 9% instead of 17%. These findings highlight that TAVI was at least as good as SAVR in high-risk patients. However, there have also been a considerable number of patients with low-estimated risk undergoing TAVI. This is not necessarily due to inappropriate indications, but may reflect the limitation of the scores (as discussed in the paragraph on risk scores, see Part 1).
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