PARTNER A: TAVR the Optimal Choice for Diabetic Patients at High Risk

AMSTERDAM, The Netherlands—In diabetic patients at high risk for surgery, transcatheter aortic valve replacement (TAVR) is a safe and effective option compared with surgery, according to an analysis of Cohort A of the PARTNER study presented on September 3, 2013, at the European Society of Cardiology Congress. TAVR reduced mortality but did not increase stroke at 1 year.

The main results of PARTNER Cohort A, published in the New England Journal of Medicine in June 2011, showed that TAVR and surgical valve replacement yield similar 12-month survival.

For current analysis, Brian R. Lindman, MD, of the Washington University School of Medicine (St. Louis, MO), and colleagues conducted a post-hoc analysis at 1 year of 657 PARTER A patients, including 275 who were diabetic and 382 who were non-diabetic.

Mortality, Symptoms Reduced with TAVR

Researchers found an interaction between diabetes status and treatment group for 1-year all-cause mortality (P for interaction = 0.048).

The as-treated cohort of diabetic patients had reduced mortality at 1 year compared with those who underwent surgery, and the pattern, though not significant, remained when the group was broken into transfemoral (n = 191) vs. transapical (n = 84) cohorts. Also, mortality trended higher for non-diabetic patients treated with TAVR (table 1).

Table 1. One-Year Mortality

There was no difference in stroke between the treatment arms, but surgery was associated with increased renal failure, dialysis lasting longer than 30 days, and major bleeding. TAVR was associated with a greater incidence of vascular complications (table 2).

Table 2. Clinical Outcomes at 1 Year: Diabetic Patients

 
Postprocedural symptoms were fewer in the TAVR arm through 30 days (P = 0.002), but the difference evened out at 6 months (P = 0.18) and 1 year (P = 0.58). Quality of life, as tested by the Kansas City Cardiomyopathy Questionnaire (KCCQ), was higher for TAVR patients vs. surgery through 30 days (P = 0.004) but again became equivalent at 6 months (P = 0.29) and 1 year (P = 0.17).

Both mild and moderate/severe postprocedural aortic regurgitation were lower in the TAVR arm through 6 months (P < 0.0001 and P = 0.052, respectively).

‘Preferred Approach’

“Our study raises the possibility that TAVR may be the preferred approach for diabetic patients with severe symptomatic aortic Stenosis who are at high surgical risk,” Dr. Lindman said, acknowledging the study’s limitations. “Diabetes status was not a prespecified subgroup analysis of the PARTNER trial, therefore our findings should be considered hypothesis generating.”

Moreover, no data was collected on diabetic medication usage, severity or duration of diabetes, microvascular complications, or glucose control, he reported.

The survival benefit of TAVR in diabetic patients needs to be confirmed in a prespecified analysis of a randomized trial, Dr. Lindman concluded, in order to “evaluate whether these findings extend to lower-risk patients” and understand how the findings may be influenced by insulin treatment and metabolic syndrome.

Standard Diabetes Definition Needed

Discussant Martine Gilard, MD, of Brest University Hospital (Brest Cedex, France), said “the positive interaction between diabetes status and survival will justify further analysis of this population.”

However, she observed, the study lacks a standard definition of diabetes. At 42%, the prevalence of diabetes in the population is “very high,” especially compared to the 20% rate in the Society of Thoracic Surgeons (STS) database. Additionally, Dr. Gilard noted, the study associated diabetes status with increased mortality and morbidity, while the STS database did not.

Dr. Lindman explained that diabetes status was determined independently at each study site. “That is a limitation,” he said. “However the higher incidence, which was somewhat surprising, would suggest that perhaps some people with more mild diabetes were being called diabetic, and that would actually move us more toward the null hypothesis. . . . The higher rate and the fact that we had the finding makes it more impressive.”

Dr. Gilard also questioned the weakness of the impact of diabetes on all-cause mortality. “It is very interesting to understand how the diabetic status protects the patients in the TAVR group,” she said.

Likening this outcome to a “diabetes paradox,” Dr. Lindman cautioned against drawing conclusions from this finding because of the substantial clinical characteristics between diabetic and non-diabetic patients. He highlighted the fact that BMI was higher in the diabetes group at 30.2 vs. 25.5 in the non-diabetes group. “There was a significant independent protective effect from a higher BMI, so that significantly confounds that comparison,” he said.

 

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Source:
Lindman BR. PARTNER: Transcatheter versus surgical aortic valve replacement in patients with diabetes and severe aortic Stenosis at high risk for surgery. Presented at: European Society of Cardiology Congress; September 3, 2013; Amsterdam, The Netherlands.

 

 

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