LAUSR

To the Editor: The field of complex, high-risk indicated percutaneous coronary intervention (CHIP) is rapidly evolving and we commend Riley and his colleagues for taking the initiative to compile these expert strategies for achieving optimal outcomes. The inaugural guidelines provide a comprehensive review of the current literature and guidance for the wide array of procedural and patient-specific difficulties that an operator may encounter. In addition, there are two key points that we think should be highlighted for CHIP procedures: radiation safety and future advancements of the field. With an increase in the technical complexity of a procedure, there is often a correlating increase in fluoroscopy time. Radiation safety should always be at the forefront of any interventional cardiologist's mind, but even more so for those performing CHIP. This is crucial for both patient safety as well as that of the operators and lab staff. Our catheterization lab C-arms have an upper limit of dose levels, which effectively caps the amount of radiation emitted even at steeper angles or increased magnification. Although this does result in a minor reduction in image quality, we have not found that this results in any significant disruption to our workflow or procedural capabilities. In addition to standard safety measures, our catheterization labs have a preprogrammed “CTO” package, whereby fluoroscopy and cine frame rates are reduced to 7.5 fps and 7.5 pps. This provides a substantial reduction in cumulative radiation exposure without sacrificing image quality. Because cine runs have a substantially higher radiation dose than fluoroscopy, our practice heavily relies on the “last image hold” feature, which allows us to review the most recent fluoroscopy run and archive it for our records. These fluoroscopy saves are more than adequate for subsequent review, eliminating the need for an additional cine run. The field of CHIP is a developing one and as such we feel that it is important to highlight some of the potential technologies that could further advance its growth. Robotic-assisted PCI has been shown to significantly reduce radiation exposure to the operator, a desirable outcome for CHIP cases as we described above. Although there are limitations to the current iteration of the robot, its potential for reducing operator radiation exposure and orthopedic injury in CHIP procedures should not be overlooked. We have found that CHIP cases can often be adapted for a hybrid approach of robotic and manual PCI, though further studies are needed to better define the appropriate patient population. Finally, coronary computed tomography angiography (CTA) coregistration with real-time fluoroscopy during CHIP, and particularly during chronic total occlusion procedures, has been shown to be feasible with the potential to improve procedural outcomes. We have found that the coronary CTA itself can provide invaluable information with regards to plaque characteristics and vessel course. Beyond that, live fusion imaging provides the operator a real-time centerline of the vessel course that automatically rotates with the C-arm. It may serve to be particularly useful for new CTO operators in approximating the vessel course, although further studies are needed to confirm this. In addition to its value for co-registration, we have recently shown that coronary CTA can be used to print personalized 3-D models to aid with procedural planning. We used a 3-D model to determine the best guide catheter for a patient with a CTO of an anomalous RCA, where we ultimately needed to manipulate a standard guide catheter to create a customized catheter. This pre-procedural step saved us from the radiation and time associated with systematically trialing guide catheters in the catheterization lab. We strongly believe that technological advances such as these will play a pivotal role in the growth of CHIP in the upcoming years.