IJCS | Volume 31, Nº4, July / August 2018

336 The FFR reflects the pressure gradient in a single vessel; on the other hand, the MS makes a comparison of the functional stenosis severity between the vessels. The perfusion defect in MPS is defined by comparison with the region of higher perfusion, considering that this region is normal, but often it is also an altered region − although less affected. 10 In the assessed sample, 38.8 % of the patients had left main coronary artery or three-vessel disease, which may have contributed to a disagreement between the results. Another factor to be considered regarding the agreement analysis is the presence of microvascular disease, which influences the FFR assessment, 10 although Figure 1 - Myocardial scintigraphy (MS), according to the fractional flow reserve (FFR). Figure 2 - Myocardial scintigraphy (MS) in the anterior descending artery (ADA) according to the fractional flow reserve (FFR). results, MPS was negative in 69% − both results showed a non-significant p value (0.413) (Figure 2). Discussion When assessing ischemia, the agreement between MPS and FFR is a weak one. 8,9 In the present study, we observed the non-agreement between the methods, although 83% of patients with positive FFR had positive MPS; the p value was not significant. Such disagreement becomes more evident in patients with multivessel disease, since MPS tends to underestimate the functional importance of the lesions. 8 Negative MS Positive MS TOTAL FFRXMS Negative FFR Positive FFR Negative MS Positive MS TOTAL FFRXMS ADA Negative FFR Positive FFR Issa et al. Comparison between Fraction Flow Reserve and SPECT in Myocardial Ischemia Int J Cardiovasc Sci. 2018;31(4)333-338 Original Article