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PARTNER: Transcatheter versus Surgical Aortic Valve Replacement in Patients with Diabetes and Severe Aortic Stenosis at High Risk for Surgery

Valvular Heart Diseases


Presenter abstract Discussant report  All the Scientific resources on ESC Congress 365

Presentation

By Brian Lindman
Other authors: Dr. Philippe Pibarot/ Canada; Dr. Rakesh Suri/ USA; Dr. Suzanne V. Arnold/ USA; Mr. Thomas C. McAndrew/ USA; Dr. Hersh S. Maniar/ USA; Dr. Alan Zajarias/ USA; Dr. Ron Waksman/ USA; Dr. Susheel Kodali/ USA; Dr. Ajay J. Kirtane/ USA; Dr. Vinod H. Thourani/ USA; Dr. E. Murat Tuzcu/ USA; Dr. Lars G. Svensson/ USA; Dr. Craig R. Smith/ USA; Dr. Martin B. Leon/ USA
Aims:
Diabetes is associated with increased morbidity and mortality after surgical aortic valve replacement (SAVR). We hypothesized that a less invasive approach with transcatheter aortic valve replacement (TAVR) might improve clinical outcomes in patients with diabetes and aortic stenosis (AS).

Methods and Results:
Among patients with severe symptomatic AS at high-risk for surgery in the as-treated population of the PARTNER trial Cohort A, we examined outcomes stratified by diabetes status of patients randomly assigned to TAVR (via transfemoral or transapical approach) or SAVR. The primary outcome was all-cause mortality at 1 year. Among 657 enrolled patients who underwent treatment, there were 275 patients with diabetes (145 TAVR, 130 SAVR).
There was a significant interaction between diabetes status and treatment group for 1 year all-cause mortality (p=0.048). Among patients with diabetes, the rates of death at 1 year from any cause were 18.0% in the TAVR group and 27.4% in the SAVR group (p=0.04). Results were consistent among patients treated via transfemoral vs. transapical routes. In contrast, among patients without diabetes, there was no significant difference in the 1-year rates of all-cause mortality by treatment group (27.8% for TAVR vs. 23.7% for SAVR, p=0.48). Among patients with diabetes, there was no significant difference in the rates of major stroke at 1 year between treatment groups (2.1% for TAVR vs. 2.7% for SAVR, p=0.87). 
TAVR was associated with lower 1-year rates of renal failure requiring dialysis (4.2% vs. 10.6%) and dialysis lasting greater than 30 days (0 vs. 6.1%) compared to SAVR in patients with diabetes (p<0.05 for both).

Conclusions:
Among patients with diabetes and severe AS who are at high-risk for surgery, this post-hoc stratified analysis of the PARTNER trial suggests that there appears to be a survival benefit, no increase in stroke, and less renal failure from treatment with TAVR compared to SAVR.

Discussant Report

Martine Gilard
Dr Lindman on behalf of The PARTNER Trial investigators have presented a comprehensive post-hoc analysis of outcomes stratified by diabetes status in patients who were randomized transcatheter (TAVI) versus surgical (AVR) aortic valve replacement in PARTNER trial cohort A.
In this study, diabetic patients treated with TAVI improved significantly the all-cause mortality at 1 year, the NHYA Class, without increasing the rate of stroke compared with diabetic patient who underwent surgery. TAVI seems to be a less invasive approach and seems also to improve clinical outcomes in diabetic patients. The positive interaction between diabetes status and treatment group may justify further analysis in this particular population.
However there are three important points to discuss.
The first and major point is the absence of definition of the diabetes in this study. The rate of so-called diabetic patients is very high: 42%. In the americain STS database including 216,245 patients treated with AVR, the rate of diabetic patients is only 20%, and 25.8% in the French study FRANCE 2.
Furthermore in the limitations of the study the authors mentioned that there were no data on diabetic characteristics of the patients. It seems therefore evident that this point is a major limitation for the study.  
The second point is the author’s hypothesis that diabetes is associated with an increased morbidity and mortality after AVR. However, again in the STS database, diabetes has no effect on mortality (1) as well as in a French series of 1,193 consecutive valve replacement performed in octogenarians since 2000 (2).
The third point is the weakness of the impact of diabetes on all cause mortalit as the Log Rank p value was 0.044. If the authors had applied a simple Chi2 test, with the number of death at 1 year, the Relative Risk is 0.65 and p value would not have been significant. The use of Chi2 test would have been possible in this study with a complete follow-up at 1 year.
On the other hand, the study is a post-hoc study with no stratification of the randomisation on diabetes status. So the rate of diabetic patients is more important in the TAVI group than in AVR (10 %). It would have been more relevant to have the baseline characteristics of the non-diabetic patients. In the study, the diabetic patients had significant lower all-cause mortality at 1 year after TAVI compared with the overall population (18% vs 24%). It is hard in that case to assess the protector effect of the diabetes status.
In conclusion, this very interesting study suggests that diabetic patients benefit from TAVI compared with AVR. However, the diabetic patients were not well defined and the magnitude of the effect is potentially over estimated due to methodological issues. Therefore, these results seem to be currently rather a suggestion than a demonstration that needs further specially designed studies.

1- Rankin JS, Hammill BG, Ferguson TB Jr, Glower DD, O'Brien SM, DeLong ER, Peterson ED, Edwards FH. Determinants of operative mortality in valvular heart surgery. J Thorac Cardiovasc Surg. 2006;131:547-57.

2- Langanay T, Flécher E, Fouquet O, Ruggieri VG, De La Tour B, Félix C, Lelong B, Verhoye JP, Corbineau H, Leguerrier A. Aortic valve replacement in the elderly: the real life. Ann Thorac Surg. 2012;93:70-7;

References


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SessionTitle:

PARTNER: Transcatheter versus Surgical Aortic Valve Replacement in Patients with Diabetes and Severe Aortic Stenosis at High Risk for Surgery

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.