Abstract 5084: Long Term Survival According to Weight Among Patients without Known Cardiac Disease and a Normal Stress SPECT: Extending the Spectrum of the Obesity Paradox
The obesity paradox, a decrease in mortality with increasing body mass index (BMI), has been described in patients with heart disease. Whether this paradox extends to referral populations without a history of cardiac disease is not well known. We assessed if obese patients in whom ischemia was excluded following referral to stress-rest myocardial perfusion SPECT manifest a lower mortality rate. 3,673 patients (60 ± 13 yrs, 36% males) with no history of heart disease and a normal stress SPECT were included in this study. Normal weight was defined as BMI 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. 942 (26%) of patients were normal weight, 1,261 (34%) were overweight and 1,470 (40%) were obese. Mean patient follow-up was 7.5 ± 3 yrs. 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 <0.0001) and the obese (event rate 1.2%/year, p <0.0001) 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 =0.54, 95% CI 0.43– 0.7) and the obese groups (HR=0.49, 95% CI 0.38 – 0.63) (Graph). In this large group of patients with both no known cardiac disease and 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 extends the spectrum of patients in whom the obesity paradox is present.