Impact of inducible ischemia by stress SPECT in cardiac risk assessment in diabetic patients: rationale and design of a prospective, multicenter trial

BACKGROUND: A prospective, multicenter trial has been designed to evaluate the impact of inducible ischemia by stress single photon emission computed tomography (SPECT) in diabetic patients and to define the role of SPECT in assessing the cardiac risk in such patients. This report presents the details and implications of the Impact of Inducible Ischemia by Stress SPECT (IDIS) trial design. METHODS AND RESULTS: Between January 2002 and September 2005, 1006 consecutive patients (649 men and 357 women; mean age, 63 +/- 9 years) with at least a 5-year history of type 2 diabetes mellitus were enrolled. All patients underwent stress-rest sestamibi SPECT imaging with physical exercise (n = 573) or dipyridamole (n = 433). SPECT studies will be analyzed by use of a 17-segment scoring system to calculate left ventricular ejection fraction, summed stress score, summed rest score, and summed difference score. The SPECT study will be considered abnormal if the summed stress score is 3 or greater. Patients with abnormal studies will be considered to have ischemia if the summed difference score is 2 or greater. CONCLUSION: The results of this trial should help to define the role of SPECT in assessing cardiac risk in diabetic patients. Furthermore, this trial will prospectively evaluate subsequent patient outcome during long-term follow-up.