ABC | Volume 113, Nº6, December 2019

Original Article Ket et al. Myocardial ischemia by SPECT and CCTA Arq Bras Cardiol. 2019; 113(6):1092-1101 (95‑100%), emphasizing its excellent performance in excluding CAD. This fact should be increasingly exploited in clinical practice, avoiding invasive exams. 3-6,8-10 SPECT assessment of myocardial perfusion can allow for better stratification of patients with intermediate stenosis and definition of therapeutic strategies, aiming at better prognosis. 11-18 On the other hand, the use of hybrid technology, which combines the anatomical information from CCTA and rubidium-82 (Rb-82) myocardial positron emission tomography (PET) perfusion imaging, presents high accuracy in CAD detection; 19-31 however, this approach is still expensive and difficult to implement clinically. Thus, we observe that CCTA can aggregate perfusion imaging and, therefore, be increasingly used as the initial test for CAD, which remains one of the leading causes of mortality in Brazil and worldwide. Nevertheless, although several studies have demonstrated the diagnostic and prognostic value of myocardial perfusion by CCTA in patients with suspected CAD, these data are still limited in the Brazilian population. Besides, it is uncertain whether the use of CCTA analysis can replace other myocardial perfusion methods, such as SPECT, especially in places where this method may not be available. The implementation of myocardial perfusion assessment by CCTA is simple and less expensive compared to other methods. Our purposes were: to evaluate the diagnostic performance of myocardial perfusion assessment by CCTA for significant obstructive CAD detection compared with SPECT; to analyze the importance of anatomical knowledge to understand the presence of myocardial perfusion defects by SPECT that cannot be identified by CCTA; and to describe SPECT false positives. Method This is an observational study that assessed patients clinically indicated to undergo myocardial scintigraphy for CAD stratification. All patients accepted and signed the informed consent form to participate in this research on myocardial perfusion assessment by CCTA. The study and the Free and Informed Term of Consent were approved by the Research Ethics Committee of Análise de Projetos de Pesquisa (CAPPessq), do Hospital Universitário Antônio Pedro (HUAP)/Universidade Federal Fluminense (UFF) number número 392.966. Patient selection for this observational study included 38 patients from our institution [Antonio Pedro University Hospital – Federal Fluminense University (HUAP-UFF)], recruited in the Nuclear Medicine service (Figure 1). The CCTA results (anatomy and perfusion) were considered as research data and were not reported to the patient's clinical Figure 1 – The selection of patients for this observational study included 38 patients from our institution [Antonio Pedro University Hospital – Federal Fluminense University (HUAP-UFF)], recruited in the Nuclear Medicine Service. CTA: computed angiotomography; CAD: coronary artery disease; SPECT: Single-photon emission computed tomography; ICF: Informed consent form. Patients referred to the Service of Nuclear Medicine (HUAP-UFF) for stratification of CAD (September 2013-March 2015) Exclusion criteria Inclusion criteria Signed an ICF 38 patients 35 patients SPECT at rest SPECT under stress Computer Tomography Service (HUAP-UFF) for performance of research protocol 3 excluded due to operational problems Calcium score CCTA + perfusion at rest Stress Perfusion Dipyridamole 0.56 mg/kg/4 minutes On the sixth minute, Tc-99m sestamibi infusion 1093