‘Obesity Paradox’ Observed in TAVR Patients

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Overweight and obese patients receiving transcatheter aortic valve replacement (TAVR) have better 1-year survival compared with their normal-weight peers, while underweight patients face more major vascular complications, according to registry findings published online September 23, 2013, ahead of print in the American Journal of Cardiology.

Masanori Yamamoto, MD, of Centre Hospitalier Universitaire Henri Mondor (Creteil, France), and colleagues assessed the impact of BMI on clinical outcomes in 3,072 TAVR patients enrolled in the FRANCE 2 registry from January 2010 to October 2011. Patients were categorized into 4 groups based on BMI:

  • Underweight (< 18.5 kg/m2; n = 95)
  • Normal weight (18.5-25 kg/m2; n = 1,355)
  • Overweight (25-30 kg/m2; n = 1,050)
  • Obese (> 30 kg/m2; n = 572)

Numerous baseline characteristics differed among the 4 groups; for example, underweight patients tended to be older and female but were less likely to have comorbidities and histories of MI and cardiac surgery (P < 0.001 for all).

While procedural success was high across the board, underweight patients had shorter hospital stays and more major vascular complications than higher-BMI patients. Postoperative survival at 30 days and 1 year increased progressively along with increasing BMI (table 1).

Table 1. Unadjusted Outcomes According to BMI

 

Underweight

Normal

Overweight

Obese

P Value

Length of Stay, days

9.6 ± 5.1

9.8 ± 7.8

10.0 ± 7.5

10.9 ± 9.2

0.034

Major Vascular Complications

11.6%

4.4%

4.8%

5.4%

0.018

Survival
30 Days
1 Year


 83.2%
67.9%

 
88.9%
73.6%

 
91.6%
77.4%

 
93.0%
80.3%

 
0.003
0.006


Multivariate Cox regression analysis attenuated the survival benefit associated with higher BMI at 30 days but not at 1 year. Underweight patients and normal-weight patients had similar mortality (table 2).

Table 2. Mortality Risk vs. Normal-Weight Group

 

Adjusted HR (95% CI)

P Value

30 Days
Underweight
Overweight
Obese

 
1.54 (0.87-2.74)
0.77 (0.58-1.03)
0.71 (0.49-1.03)

 
0.14
0.075
0.071

1 Year
Underweight
Overweight
Obese

 
1.25 (0.78-2.00)
0.81 (0.66-1.00)
0.74 (0.57-0.97)

 
0.35
0.050
0.029


Adjusted risk of major vascular complications was similar for normal-weight, overweight, and obese patients. However, the underweight group again was at higher risk compared with the normal-weight group (adjusted HR 2.33; 95% CI 1.17-4.66; P = 0.016).

Age, Background Cardiovascular Disease Cited

According to Dr. Yamamoto and colleagues, the current findings suggest that the so-called obesity paradox may be present in the TAVR population.

Carl J. Lavie, MD, of Ochsner Medical Center (New Orleans, LA), pointed out to TCTMD that the paradox has already been documented in conjunction with “virtually all cardiovascular disease,” including hypertension, heart failure, PAD and CAD, as well more generally in elderly patients.

The concept “is in a way counterintuitive,” Dr. Lavie acknowledged in a telephone interview. “If obesity leads to more heart disease, then why do the obese with heart disease do better?”

A likely explanation, he said, is that low BMI can only be explained by genetic predisposition or, “something different about you. Because in our society, with all the food around and not doing the same physical activity now as 5 decades ago, the amount of calories you have to burn in your daily [life] can be pretty low. . . . For most heart disease, if you have a good BMI and get heart disease despite that BMI, obviously you developed heart disease for a whole different reason.”

What’s unique about the current paper, Dr. Lavie said, is that obesity would not be expected to raise the risk of aortic stenosis. “Mostly, aortic valve disease happens just because of aging and wear and tear on the valve,” he noted, attributing the patterns seen here to background cardiovascular disease and the fact that the population is “very elderly, with an average age in the low to mid 80s.”

A Focus on the Underweight

If clinicians treating heart disease patients are concerned about BMI, they should focus their efforts on the underweight, Dr. Lavie commented. There are no data to support telling elderly patients who are overweight or mildly obese to lose weight, he said. “[Conversely,] no one is actually recommending people to gain weight, but I think when you’re dealing with [elderly heart-disease patients] it would be hard to argue with the fact that thinner patients would gain something from gaining muscle.”

Dr. Yamamoto and colleagues comment that “underweight elderly patients may be considered fragile and are high-risk surgical patients among the [TAVR] population. . . . Continuous efforts are needed to reduce the risk of procedural complications and determine the optimal post- and pre-[TAVR] management in underweight patients.”

 


Source:
Yamamoto M, Mouillet G, Oguri A, et al. Effect of body mass index on 30- and 365-day complication and survival rates of transcatheter aortic valve implantation (from the FRench Aortic National CoreValve and Edwards 2 [FRANCE 2] registry). Am J Cardiol. 2013;Epub ahead of print.

 

 

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Disclosures
  • Drs. Yamamoto and Lavie report no relevant conflicts of interest.

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