The potential for PET-guided revascularization of coronary artery disease

Excerpt

Over the past two decades, positron emission tomography (PET) has been very useful for the diagnosis and staging of various cancers and successful for guiding therapy [1]. A striking illustration is the use of ¹⁸F-fluorodeoxyglucose (FDG) PET to guide chemotherapy in patients with lymphoma. For example, in patients with limited-stage Hodgkin’s lymphoma, FDG PET can be performed after two cycles of chemotherapy to establish disease activity. Persistent disease on PET will trigger a change in chemotherapeutic agents and higher radiation therapy doses, while a negative PET study will result in shorter therapy and lower radiation therapy doses with better patient outcomes [2, 3]. This is one of many effective PET-guided interventions in oncology. In contrast, demonstration of the effectiveness of PET-guided therapy for cardiovascular applications has been more challenging. For example, the PARR-2 trial [4] was a randomized controlled trial designed to evaluate the role of myocardial viability assessment with FDG PET to guide revascularization in patients with severe left ventricular dysfunction. Although the study concept was supported by much clinical evidence and rooted in strong physiology, it failed to demonstrate a significant benefit for the PET-guided management versus standard care. Interestingly, a single-site post hoc analysis showed that the adverse outcome rate was significantly lower when revascularization was concordant with the PET recommendation, compared to revascularization discordant with the PET recommendation [5]. These better outcomes with concordant PET and revascularization may reflect optimal patient management in centers with integrated imaging, heart failure and surgical teams and clinical management teams, a factor which was not accounted for in the original trial. Similarly, other clinical factors may influence the decision for a specific therapy more than the PET result and lead to discordant PET revascularization decisions. Thus, implementation of a robust prospective clinical trial to determine the efficacy of cardiac PET-guided therapy may be particularly difficult. …