The ACC NCDR CathPCI Registry is an exam- ple of a national registry to fulfill the goals of assessing and benchmarking quality and outcomes. 8. Future Challenges Although this latest guideline reflects significant advance- ments in the field of PCI, there remain future challenges to the formulation and updating of guidelines for PCI. The proliferation of studies comparing the many newer drugs and devices with older therapies (or other newer therapies), often using different or novel study endpoints, endpoint definitions, and noninferiority designs, pose increasing challenges to objectively evaluating newer therapies and generating recom- mendations for their use. Numerous potential advances in the field of PCI, including intracoronary stem cell infusions for chronic and acute ischemic heart disease, designer drugs, novel intracoronary imaging technologies such as optical coherence tomography and virtual histology, new stent com- position and designs (eg, drug-eluting, biodegradable, bifur- cation), and drug-eluting balloons were considered for formal evaluation by the current writing committee, but it was thought that there were insufficient data at present to formu- late any formal recommendations on these topics. These and other emerging technologies and treatments will need to be addressed in future PCI guidelines. Finally, with this proliferation of new technology, the amount of data generated in the evaluation of these potential therapeutic advances will grow dramatically, adding signifi- cant challenges to future guideline generations. Of note, the Web site www.clinicaltrials.gov currently lists several hun- dred PCI-related clinical trials. 