ABC | Volume 114, Nº2, February 2020

Update Update of the Brazilian Guideline on Nuclear Cardiology – 2020 Arq Bras Cardiol. 2020; 114(2):325-429 Recommendation class IIa • Patients suffering from chest pain – resting ECG to determine whether or not pain is of ischemic origin ( level of evidence: B ). • Patients with uncomplicated anterior wall AMI, with the objective of determining the exact size of the ischemic lesion ( level of evidence: B ). In stable patients with evolving ACS, echocardiography associated with pharmacological stress before hospital discharge may identify induced ischemia and assist in risk stratification and medical management of immediate follow- up (6 to 12 weeks), especially if LVEF values are below 40%. Coronary angiotomography: Many studies have shown that coronary angio-CT is an important tool for evaluating acute chest pain, especially in low- to intermediate-risk patients. 169-172 It is a safe procedure for diagnosing ACS, and it is able to reduce intra-hospital follow-up time and contribute to cost reduction. In the Rule Out Myocardial Infarction by Cardiac Computed Tomography II (ROMICAT II) Study, duration of hospital stay was significantly lower in patients stratified via angio-CT in comparison with the group submitted to conventional evaluation (23.2 ± 37 hours vs . 30.8 ± 28 hours). 173 There was also a significant increase in percentage of patients discharged from the emergency unit in the group stratified with this method (46.7% vs . 12.4% p < 0.001), in spite of higher costs associated with angio-CT and the greater tendency to refer patients for catheterization and revascularizations. Based on recent publications, low- to intermediate-risk patients with acute chest pain, non-diagnostic ECG, and negative markers of necrosis have Class-I recommendation and level of evidence A for undergoing angio-CT, especially considering the method’s NPV. There are, nevertheless, limitations in the presence of STEMI and NSTEMI (Figure 16) (with the exception of coronary dissection) and known CAD or prior revascularization where the existence of intracoronary prostheses (stents) and calcium may negatively influence the exam’s specificity for its proposed aim, leaving the possibilities of functional evaluation and global repercussion. Finally, it is necessary to consider exposure to elevated doses of radiation and lower image quality for the exclusion of pulmonary embolism, aortic dissection, or ACS (triple rule-out). 174 Myocardial perfusion scintigraphy (MPS): Within the scope of its applications ( See the Indications chapter ), the following stand out: indirect evaluation of coronary reserve Figure 16 – Clinical scenarios of patients who present with chest pain at emergency units. Situations of ACS diagnosed as STEMI and UA/NSTEMI correspond to orientations established by pertinent guidelines. In the condition of possible or suspected ACS, the previously described sequences of diagnostic investigation and stratification are recommended. ACS: acute coronary syndrome; CAD: coronary artery disease; MPS: myocardial perfusion scintigraphy; NL: normal; NSTEMI: non-ST- segment elevation acute myocardial infarction; STEMI: ST-segment elevation acute myocardial infarction; UA: unstable angina. SYMPTOMS SUGGESTIVE OF ACS POSSIBLE ACS NL/NON-DIAGNOSTIC ECG, NL MARKERS SERIAL ECG AND MARKERS NEGATIVE ISCHEMIA TEST DETECTION OF ANATOMICAL CAD RESTING MPS OUTPATIENT TREATMENT POSITIVE ADMISSION TO HOSPITAL ESTABLISHED ACS STEMI GUIDELINES UA/NSTEMI GUIDELINES 355