IJCS | Volume 31, Nº4, July / August 2018

334 mean pressure distal to the coronary lesion by the mean aortic pressure during maximal adenosine-induced vasodilation. The FFR has a normal value of 1, and values ​less than 0.8 indicatemyocardial ischemia. Studies have shown that coronary vessels with FFR ≥ 0.8 can be clinically treated, with cardiovascular event rates similar to those of patients with normal noninvasive tests (< 1% per year). Patients with FFR ≤ 0.8 could benefit from percutaneous or surgical revascularization procedures. 1-3 Although the FFR has its defined role in moderate lesions and is not very useful in angiographically severe lesions, it helps in the decision-making regardingwhen to revascularize patients with multivessel disease. In these patients, it helps to define the revascularization strategy, as well as to better evaluate its extent, according to the functional evaluation of stenosis in critical coronary sites. 4 Myocardial perfusion scintigraphy (MPS) with tomographic images has been validated by several studies in the evaluation of diagnosis and prognosis for patients at risk of cardiovascular events. The functional repercussion of coronary lesions constitutes one of the main purposes of the method, which is based on the perfusion deficit assessment in myocardial segments irrigated by partially occluded arteries. Risk stratification is based on the ability to identify patients according to the test results. SPECT with normal or slightly altered perfusion has an excellent prognosis, with a lowmortality risk (< 1%) per year. The risk associated with perfusion alterations varies according to the ischemia extent and severity. The greater the perfusion defects, the higher the likelihood of future events. In those with moderate perfusion defects, the incidence of events is 1 to 3% per year, being > 3% in patients withmajor perfusion defects. 5 Most percutaneous coronary interventions are performed based on angiographic criteria alone, with no objective evidence of myocardial ischemia. Coronary angiography has limitations in establishing functional severity, because the stenosis degree of a lesion does not always correlate with functional impairment in the myocardium.6 Thus, it is important to complement anatomical data with functional tests capable of adequately guiding the therapeutic approach regarding a myocardial revascularization procedure. Several studies have been carried out to evaluate the agreement between the FFR with functional methods (MPS, dobutamine stress echocardiogram and exercise testing) to define the presence of myocardial ischemia, with the FFR having the advantage of being specific for each vessel and obstruction. 7 In multi-vessel patients, MPS tends to underestimate or overestimate the functional importance of coronary stenosis when compared to FFR. 8 The functional tests are performed in a minority of patients referred to coronary angioplasty at Instituto Nacional de Cardiologia . In this sense, the FFR can be a useful tool in the hemodynamics room to aid in decision-making regarding whether or not to perform a percutaneous coronary intervention, saving time and costs to the health system. The objective of the present study was to compare the functional analysis between FFR and MPS in patients with moderate lesions at the coronary angiography. Methods This is a prospective, observational study of patients of both genders, aged 18 years or older, admitted to the Department of Coronary Disease unit or referred to the Hemodynamic Service of Instituto Nacional de Cardiologia , who had an FFR indication after the coronary angiography by themultidisciplinary “Heart team”. The sample size of 47 patients was selected by convenience. Patients with no previous MPS were submitted to the examination. Coronary lesions were classified as moderate (between 50 and 70%) and severe (≥ 70%) according to visual estimation. Patients with moderate lesions and those for whom there was doubt regarding the indication of myocardial revascularization were included in the study. Patients with chronic occlusion, ST-segment elevation acute myocardial infarction, unstable patients, those with severe valvular disease or cardiomyopathies from other causes, patients with contraindications to the use of adenosine and to scintigraphy (pregnant women, infants and women with suspected pregnancy) were excluded from the study. The study was approved by the Ethics and Research Committee of Instituto Nacional de Cardiologia , and all the participants agreed to sign the Free and InformedConsent Form. The present study has no sources of funding. Fractional flow reserve measurement Coronary catheterization was performed with 6 and 7F guide catheters. Prior to the angiography, 10,000 u of intravenous heparin and intracoronary nitroglycerin at a dose of 0.25 to 0.5 mg were administered. Then, pressure measurements were performed in vessels with stenosis ≥ 50% by visual estimation using a guidewire with a Issa et al. Comparison between Fraction Flow Reserve and SPECT in Myocardial Ischemia Int J Cardiovasc Sci. 2018;31(4)333-338 Original Article