Impact of weight on long-term survival among patients without known coronary artery disease and a normal stress SPECT MPI

Background: While obesity has been shown to be associated with a worse mortality, an "obesity paradox"-lower mortality in obese patients-has been noted among many patients with coronary artery disease (CAD). The extent to which an obesity paradox operates among patients with only suspected CAD, is not well determined. Methods and Results: A total of 3,673 patients (60 ± 13 years, 36% males) with no history of heart disease and a normal stress SPECT were included in this study. Normal weight was defined as BMI of 18.5-24.9 kg · m²; overweight 25-29.9 kg · m², obese >30 kg · m². The baseline clinical risk factors were recorded for each patient. The end point of the study was all-cause mortality. Of patients 942 (26%) were normal weight, 1,261 (34%) were overweight, and 1,470 (40%) were obese. Mean patient follow-up was 7.5 ± 3 years. When compared to normal weight patients (event rate 3.2%/year), there was a lower incidence of death in the overweight (event rate 1.5%/year, P < .0001) and the obese (event rate 1.2%/year, P < .0001) groups. After controlling for baseline risk factors, using a reference HR = 1 for normal weight patients, there was a lower risk of death in the overweight (HR = .54, 95% CI .43-.7) and the obese groups (HR = .49, 95% CI .38-.63). Conclusion: In patients without known cardiac disease and a normal stress SPECT, overweight and obese patients had a lower rate of all-cause mortality compared to normal weight patients over long-term follow-up. This study substantially extends the spectrum of patients in whom the obesity paradox is present.