Possible improvement of the SYNTAX score by individualized coronary angiographic area at risk assessment validated by myocardial perfusion SPECT

Background:
The fractional flow reserve (FFR) is a simple, reproducible and reliable physiological index to indicate the severity of lesions in coronary arteries. Because decision-making on myocardial revascularization should be guided by reliable demonstration of inducible ischemia, FFR has been recently suggested to incorporate into the SYNTAX scoring (SS) system originally based on information from angiography alone. This combined approach is called Functional SYNTAX Score (FSS). Both in the SS and FSS the Leaman weighing score is used for the evaluation of the left ventricular areas affected by the lesion using only the two coronary circulation systems (left or right dominance) for the scoring.
Aim:
Our aim is to create a more detailed analysis of the coronary types in order to find the area at risk precisely, and to investigate the correlation between perfusion abnormalities detected by single-photon emission computed tomography (SPECT) and fractional flow reserve (FFR) by using a complex cardiac database management program, the Holistic Coronary Care (HCC) and to compare its efficacy to the selection of optimal mode of revascularization (either PCI or CABG) with the FSS. Modified Functional SYNTAX Score (MFSS) was defined using this individualized area at risk determination.
Methods:
SS, FSS and MFSS were calculated from 35 patients after fractional flow reserve measurements. These scores were compared to the summed perfusion reversibility score (SRS) detected on SPECT studies.
Results:
Linear regression analysis revealed significant correlation between the SRS and the SS, the FSS (r=0.36, p=0.03 and r=0.57, p=0.001, respectively), and we found even more tight correlation between the SRS and MFSS (r=0.59, p<0.001).
Conclusion:
These preliminary data show that, with the individual circulation functional score specifically defined by our HCC program, it is possible to determine and predict left ventricular segment-related coronary lesions with better correlation than the Leaman weighing score. This area at risk determination can form a basis of the modification of the (functional) SYNTAX Score.