1. In this study of patients undergoing PET myocardial perfusion imaging, those with greater measured ischemia had improved overall and cardiac survival with early revascularization compared to medical therapy alone.
2. An ischemia threshold of 5% was determined, above which patients were observed to have greater benefit with early coronary revascularization compared to pharmacotherapy.
Evidence Rating Level: 2 (Good)
Study Rundown: For patients with stable coronary artery disease the use of invasive revascularization has not demonstrated any survival or cardiovascular benefit compared to standard medical management. Identifying high-risk patients through myocardial perfusion imaging (MPI) has been one proposed strategy for selecting individuals who may benefit from coronary revascularization. Positron emission tomography (PET) use in MPI evaluation has improved image resolution, lower radiation exposure, improved diagnostic accuracy, and shorter acquisition time compared to standard imaging techniques. The current study sought to evaluate whether PET MPI may identify patients who would benefit from revascularization compared to medical management in a modern cohort. The study found that significant ischemia on PET MPI predicted improved overall and cardiovascular mortality with early revascularization with a threshold ischemia level of 5%.
The current study supports the use of PET MPI for selecting patients at risk for death or major adverse cardiovascular events and suggests a threshold potential ischemia value for which revascularization may be considered. The study is hypothesis generating and results should be confirmed in prospective studies. The main strength of the study is the large contemporary cohort of consecutively undergoing standardized PET MPI testing. The limitations of the study include the single-center, observational design which may influence the outcome with selection bias.
In-Depth [retrospective cohort]: This study is a retrospective cohort of consecutive adult patients who underwent rest and stress rubidium-82 (Rb82) PET MPI within the Saint Luke’s Health System between January 1, 2010, and December 31, 2016. Patients were excluded if they had known cardiomyopathy (EF<40%) or non-diagnostic results. The primary endpoint was all-cause mortality and cardiac mortality was a secondary endpoint. Early revascularization was defined as percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABG) within 90 days of PET MPI assessment.
A total of 16,029 patients were included in the study with a median follow up of 3.7 years. More than one third (36.8%) of patients had ischemia measurable on PET MPI, and 2,160 patients (13.5%) had more than 10% ischemia. The cohort included 1,107 patients who underwent PCI within 90 days and 170 who had CABG. Patients with greater ischemia had improved survival with early revascularization (P<0.001 for interaction). An ischemia threshold of 5% (with upper limit of 95% CI of 10%) had benefit with early revascularization compared to medical therapy.
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