The functional SYNTAX score - a huge step forward or research in motion?

In a recent manuscript in the Journal of the American College of Cardiology, the newly introduced "functional SYNTAX score" (FSS) was found to be a better tool to assess the extent and severity of coronary artery disease than the SYNTAX score (SS) and has reclassified 1/3 of the studied cohort into lower-risk categories. Besides being more invasive, costly, and time consuming, FSS still suffers from inherent deficiencies of its own. Like SS, FSS does not incorporate clinical risk predictors and consequently is a suboptimal tool for predicting PCI risk. FSS is not supported by a wealth of contemporary outcome data in a wide range of patient and lesions subsets. Key unanswered questions are whether PCI of hemodynamically significant lesions (FFR <0.80) is superior to optimal medical therapy (OMT) and whether complete revascularization yields considerably better outcomes than partial revascularization. Since partial revascularization is still an option, operational FSS (taking into account only the FSS of lesions subject to PCI) combined with a clinical risk score will probably better predict the procedural risk of the planned PCI.