The economic implications of noninvasive molecular testing for cardiac allograft rejection.

Endomyocardial biopsy is the mainstay for monitoring cardiac allograft rejection. A noninvasive strategy--peripheral blood gene expression profiling of circulating leukocytes--is an alternative with proven benefits, but unclear economic implications. Financial data were obtained from five cardiac transplant centers. An economic evaluation was conducted to compare the costs of outpatient biopsy with those of a noninvasive approach to monitoring cardiac allograft rejection. Hospital outpatient biopsy costs averaged 3297 US dollars, excluding reimbursement for professional fees. Costs to Medicare and private payers averaged 3581 US dollars and 4140 US dollars, respectively. A noninvasive monitoring test can reduce biopsy utilization. The savings to health care payers in the United States can be conservatively estimated at approximately 12.0 million US dollars annually. Molecular testing using gene expression profiling of peripheral circulating leukocytes is a new technology that offers physicians a noninvasive, less expensive alternative to endomyocardial biopsy for monitoring allograft rejection in cardiac transplant patients.

Simultaneous assessment of fractional and coronary flow reserves in cardiac transplant recipients: Physiologic Investigation for Transplant Arteriopathy (PITA Study).

BACKGROUND: The utility of measuring fractional flow reserve (FFR) to assess cardiac transplant arteriopathy has not been evaluated. Measuring coronary flow reserve (CFR) as well as FFR could add information about the microcirculation, but until recently, this has required two coronary wires. We evaluated a new method for simultaneously measuring FFR and CFR with a single wire to investigate transplant arteriopathy. METHODS AND RESULTS: In 53 cases of asymptomatic cardiac transplant recipients without angiographically significant coronary disease, FFR and thermodilution-derived CFR (CFRthermo) were measured simultaneously with the same coronary pressure wire in the left anterior descending artery and compared with volumetric intravascular ultrasound (IVUS) imaging. The average FFR was 0.88+/-0.07; in 75% of cases, the FFR was less than the normal threshold of 0.94; and in 15% of cases, the FFR was < or =0.80, the upper boundary of the gray zone of the ischemic threshold. There was a significant inverse correlation between FFR and IVUS-derived measures of plaque burden, including percent plaque volume (r=0.55, P<0.0001). The average CFRthermo was 2.5+/-1.2; in 47% of cases, CFRthermo was < or =2.0. In 14%, the FFR was normal (> or =0.94) and the CFR was abnormal (<2.0), suggesting predominant microcirculatory dysfunction. CONCLUSIONS: FFR correlates with IVUS findings and is abnormal in a significant proportion of asymptomatic cardiac transplant patients with normal angiograms. Simultaneous measurement of CFR with the same pressure wire, with the use of a novel coronary thermodilution technique, is feasible and adds information to the physiological evaluation of these patients.