Cost-Effectiveness of Cardiac Magnetic Resonance Imaging in the Diagnosis of Cardiac Allograft Vasculopathy as Well as the Detection of Myocardial Inflammation Associated with Treatment-Requiring Cellular Rejection

Abstract

The purpose of this study is to assess the cost-impact of cardiac magnetic resonance imaging (CMR) and its advantages over conventional cardiac catheterization to detect cardiac allograft vasculopathy (CAV) and myocardial inflammation derived from possible rejection in heart transplant (HTx) recipients. A sizable institutions still perform an endomyocardial biopsy (EMB) and coronary artery angiogram (CAG) in routine practice. Non-invasive diagnostic tools such as echocardiography and gene expression profiling have been reported as a possible alternative to EMBs, but its application is limited. Stress echo is a powerful tool for sorting those who require invasive assessment, but it cannot detect ongoing CAV. CMR is free from radiation exposure and allows the visualization of coronary artery narrowing without using contrast agents. We estimated medical care expense needed for rejection and CAV surveillance for HTx recipients at 3 years to 15 year-posttransplant in Japan (n=320), consisting of those with 10 % rejection rate up to 5 years and 20% CAV occurrence thereafter, as a hypothetical cohort. Three models were created. Model-1: Annual investigation using CMR-angiography to assess CAV, and T2W imaging to detect myocardial inflammation. For patients with a suspicion of the development of rejection or CAV, EMBs and CAG are performed. Model-2: Annual evaluation using CAG and EMBs up to 10 years posttransplant. After 10 year-posttransplant, the invasive procedure is done as needed. Model-3: Using echocardiography as a primary modality to detect rejection. CAG biennial and EMBs if any change in echo. If patients never developed rejection or CAV, Model-1 is the least costly with ¥228,800 to 324,860 per patient, whereas Model-2 costs ¥1,064,000 to 2,190,000 and Model-3, ¥445,200 to 689,000, respectively. When we include patients with rejection or CAV according to a hypothetical cohort, Model-1 and Model-3 were equally cost-effective. When we set sensitivity and specificity of CMR and echo as 70%, 80% and 70%, 90%, respectively, Model-1 is most cost-effective with sufficient diagnostic accuracy. Utilization of CMR as an annual follow-up tool in HTx recipients would be beneficial from a viewpoint of medical economics.