Abstract 1775: Prognostic Value of Exercise and Dobutamine Positron Emission Tomography
Introduction Positron emission tomography (PET) is commonly performed using vasodilator stress, but exercise and dobutamine stress is available to patients with contraindications to vasodilators. Vasodilator PET appears to have prognostic value, however the prognostic value of PET using stressors which induce myocardial ischemia have not been well evaluated.
Hypothesis To evaluate the prognostic value of myocardial demand ischemia induced by treadmill exercise and dobutamine PET.
Methods 124 patients (mean age = 61.29 ± 10.73 years; 87 men) had treadmill exercise or dobutamine Rb-82 or N-13 ammonia PET. Images were assessed qualitatively using a 17-segment model and a semi-quantitative visual score (five-point scale) to calculate the summed stress score (SSS). Images were categorized as normal (SSS<4), abnormal (SSS ≥ 4) or inconclusive (SSS< 4 and suboptimal treadmill exercise or dobutamine stress). Follow-up was performed to ascertain outcomes (cardiac death, nonfatal MI and/or late revascularization.
Results Of the 124 patients, 46 (37.1%) had a normal PET, 15 (12.1%) had an inconclusive study, and 63 (50.1%) had an abnormal PET (mean follow up 2.8 ± 1.4 years). There were no deaths or non-fatal MI but 1 late revascularization (annual event rate = 1.7%) in the group with a normal PET. Abnormal PET MPI group had 15 cardiac events (1 cardiac death, 4 nonfatal MI, and 10 late revascularization) with an annual event rate of 13.0% (p = 0.002).
Conclusions Though small, this study suggests that myocardial PET perfusion defects resulting from demand ischemia induced by treadmill exercise and dobutamine stress may have prognostic value.