**12. The future of research in complex coronary artery disease**

The approach to the management of complex CAD will continue to change with exponential growth of knowledge in this area. The majority of clinical trials involving CABG and PCI were largely based on complete revascularization of lesions greater than 50 percent [45]. Use of FFR has shown that PCI with DES of moderately severe lesions (50-70 percent) guided by angiog‐ raphy alone compared with PCI of lesions guided by both angiography and hemodynamic significance (FFR< 0.80) may actually confer a higher rate of death and MI [73]. Given our knowledge of this finding, the SYNTAX trial (where the threshold for revascularization was also a stenosis of 50 percent or greater) may conceivably have different results if FFR was used to guide therapy. Furthermore, investigations with the new second-generation DES, a now better understanding of how to utilize FFR and definition of the impact of coronary complexity may serve as a guide to better define the populations that may benefit from PCI versus CABG.

The other area requiring more research is in the arena of collaboration for decision-making in multivessel disease. The Heart Team, although a promising concept would benefit from formal validation. We also need to better define what type of institutions and what type of cases would most benefit from formal evaluation with a Heart Team approach. Furthermore as these decisions become more complex, we will also need to find better methods/mechanisms of informed balanced patient involvement in the final management decision.

Complex CAD remains a challenging area both from the scientific and the clinical point of view. The goal should be to build on the research foundations in the management of MVD CAD thus far and continue to improve our understanding of how to better manage and care for patients with complex CAD.

