In Vivo Imaging of Acute Cardiac Rejection in Human Patients Using ^99mTechnetium Labeled Annexin V

Annexin V binds phosphatidylserine moieties on apoptotic cells. This study reports the initial experience at Stanford University Medical Center with ^99mTc-labeled annexin V imaging as a noninvasive measure of apoptosis in acute cardiac rejection. Ten cardiac transplant patients had ^99mTc Annexin V imaging and endomyocardial biopsy (EMB) performed within 24h. No complications related to ^99mTc annexin V administration occurred. Eight patients had ISHLT grade of acute rejection of 1A or less. Five patients had two or more areas of uptake noted in the right ventricle on imaging studies. Two of these patients had positive biopsies: one patient had grade 2 rejection with two focal uptake areas and another had grade 3A rejection with three foci. An additional five patients had either one or zero hot spot areas and corresponding negative EMBs. ^99mTc-annexin V appears to be well tolerated and may identify patients with acute cardiac rejection.