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12-12-2011 | Cardiology | Article

BMI predicts survival after aortic valve replacement


Free abstract

MedWire News: Patients who undergo aortic valve replacement (AVR) surgery for aortic stenosis (AS) with or without concomitant coronary artery bypass grafting (CABG) show better survival if they are moderately obese than if they are either normal weight or extremely obese, study findings show.

"Our findings indicate a strong and significant adjusted association between body mass index (BMI) and 30-day and long-term mortality," say William Roberts (Baylor University Medical Center, Dallas, Texas, USA) and colleagues.

For the study, the researchers analyzed excised stenotic aortic valves from 865 adults who underwent AVR for AS, with or without a first simultaneous CABG procedure.

Mortality data was obtained from medical records for deaths during hospitalization at the time of AVR and from the Society of Thoracic Surgeons national database, or from the Social Security Death Index for deaths occurring after hospitalization.

Propensity-adjusted analysis showed that patients with a BMI in the low 30s had a decreased risk for 30-day and long-term (9-year follow-up) mortality compared with patients with BMIs in the mid-20s or over 40 kg/m2.

Of the 14 factors analyzed, age, aortic valve area, 30-day mortality, and type of valve were the only factors that significantly differed among the four BMI groups (≤25, 26-30, 31-40, and >40 kg/m2).

The highest percentage of overweight patients was observed among those aged 51-70 years (76%), followed by those aged 21-50 years (72%) and 71-95 years (59%).

Aortic valve area was inversely related to BMI, and the type of substitute valve inserted also varied with BMI. Indeed, the greater the BMI, the higher the likelihood that mechanical prosthesis was used, while a bioprosthesis was most often used among those with a lower BMI.

Of the 209 patients with a mechanical prosthesis, 73% were overweight (BMI >25 kg/m2), while 65% of the 649 patients with a bioprosthesis were overweight.

The researchers found no significant difference among the groups for concomitant CABG, type of native aortic valve excised, weight of the operatively excised aortic valves, and total length of hospital stay.

The findings are published in the American Journal of Cardiology.

By Ingrid Grasmo

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