PARTNER: Post-TAVR Survival Higher in Overweight, Obese Patients

Overweight and obese patients undergoing transcatheter aortic valve replacement (TAVR) have lower mortality risks compared with normal and underweight patients, according to an analysis of data from the PARTNER trial released this week at TCT 2014. The findings, which embody the so-called obesity paradox, were confirmed even after adjustment for possible confounders.

Danny Dvir, MD, of St. Paul’s Hospital in Vancouver, Canada, and colleagues evaluated a total of 2,519 patients from the PARTNER trial who underwent TAVR procedures. They stratified the patients by BMI and found that while heavier patients tended to be younger and have lower baseline STS scores and 6-minute walking test results, they had better survival compared with lower-weight patients (see Table).

Propensity matching that adjusted for imbalances between the obese and normal-weight patients confirmed the results for 1-year mortality (18.7% vs. 29.4%; P=.002). On multivariate analysis, obesity was an independent predictor of 1-year survival after TAVR compared with both normal weight (OR 1.37; 95% CI 1.05-1.78; P=.02) and underweight (OR 2.13; 95% CI 1.4-3.22; P<.001) patients.

Dvir told TCT Daily that the results of propensity matching negate the common claim that the obesity paradox is caused by differences in baseline characteristics.

“The mechanism in which non-morbid obesity is associated with improved outcomes is controversial,” he continued, adding that one theory suggests normal-weight patients have a higher rate of non-purposeful weight loss and lower muscle strength. “Some consider patients with normal weight living in Western society as actually having a signal for cachexia.”

Though this paradox has been studied extensively in other conditions and procedures, this is the first large evaluation of valvular heart disease patients treated with standard therapy, Dvir said. Although the paradox has yet to be fully explained, he noted, there are still a number of clinical implications of the findings, especially related to patient screening.

“We have learned that underweight patients … have poor outcomes after [surgical aortic valve replacement] or TAVR. Valve implantation in some underweight patients may be futile,” he said, adding that morbidly obese patients have poor perioperative results but excellent longer-term survival. “Hence, the immense importance of excellent procedural and periprocedural care in morbidly obese patients,” Dvir concluded.