Background: The rest/stress sequence in myocardial perfusion single photon emission computed tomography (SPECT) (MPS) permits evaluation of rest images before stress testing, allowing the identification of unexpected perfusion defects (PDs). We sought to study the angiographic correlates of these resting PDs.
Methods and results: This study comprised 139 consecutive patients with no history of myocardial infarction referred for MPS whose stress test was canceled because of the observation of unexpected resting PDs (rest group). Of these, 60 patients (43.2%) were referred for angiography after MPS (6.0 +/- 11.5 days). Angiographic referral rates and results were compared with those of a diagnostic population (n = 3565) who demonstrated stress-induced PDs (stress group) on rest/stress MPS. The mean age in the rest group was 73 +/- 12.5 years, and 73% were men. The frequency of referral for angiography was higher in the rest group (43.2% vs 19.8%, P <.0001). In addition, the rest group more frequently had significant coronary artery disease (CAD) (>/=70%) (95% vs 80%, P =.008) and critical CAD (>/=90%) (80% vs 66%, P =.038).
Conclusion: The rest/stress sequence for MPS enables the identification of patients with unexpected resting PD, usually resulting from critical CAD, in whom unnecessary stress testing can be avoided.