Synergistic effect of coronary artery disease risk factors on long-term survival in patients with normal exercise SPECT studies.

BACKGROUND: Normal exercise single-photon emission computed tomography (SPECT) studies are associated with a low event rate (<1.0%/year) during short-term follow-up. The influence of cardiac risk factors on long-term outcomes in such patients has not been well studied. MATERIAL AND METHODS: 2,597 patients (55 ± 12 years, male 41%) without a history of heart disease and a normal exercise SPECT between the years 1995 and 2006 were followed for a mean 6.8 ± 3.1 years for all-cause mortality assessed for using the Social Security Death Index. Baseline clinical risk factors and other clinical information were recorded for each patient and compared to outcomes. RESULTS: The mortality rate was 0.9%/year for our overall study population but varied according to individual baseline risk factors. Three coronary artery disease (CAD) risk factors were significant predictors of all-cause mortality: hypertension, diabetes, and smoking. When all three were absent, long-term all-cause mortality rate averaged 0.2%/year and when all three were present, all-cause mortality averaged 1.8%/year, constituting a 5.7-fold adjusted increase in risk (95% CI 2.7-12.8, P < .0001). CONCLUSIONS: During follow-up, annualized mortality rate varies markedly according to the number of CAD risk factors in patients without known heart disease and a normal exercise SPECT stress. Despite overall excellent long-term prognosis of a normal exercise SPECT, the burden of traditional CAD risk factors exert a strong synergistic influence on long-term survival and warrant aggressive treatment in this patient population.

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 x m(2); overweight 25-29.9 kg . m(2), obese >30 kg x m(2). 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.