ALLOGRAFT VASCULOPATHY Early Alterations of Myocardial Blood Flow Reserve in Heart Transplant Recipients With Angiographically Normal Coronary Arteries Nicolas Preumont, MD, a Guy Berkenboom, MD, a Jean-Luc Vachiery, MD, a Jean-Luc Jansens, MD, b Martine Antoine, MD, b David Wikler, MS, c Philippe Damhaut, PhD, c Serge Degre ´, MD, a Andre ´ Lenaers, MD, c and Serge Goldman, MD c Background: The evaluation of the coronary reserve provides valuable information on the status of coronary vessels. Therefore, we studied with positron emission tomography (PET) and 13N-ammonia the myocardial blood flow (MBF) reserve in heart transplant recipients free of allograft rejection and with angiographically normal coronary arteries early after heart transplantation (HTx). The MBF reserve was calculated as the ratio between MBF after dipyridamole injection and basal MBF normalized for the rate-pressure product. Methods: Patients were studied within 3 months (group A, n = 12) or more than 9 months (group B, n = 12) after HTx. Five patients have been studied both during the early and late period after HTx. Results were compared to those obtained in 7 normal volunteers (NL). Results: Group A recipients had a significantly lower dipyridamole MBF (in ml/min/100 gr of tissue) than that of group B recipients (142  34 vs 195  59, p  0.05). This resulted in a significant decrease in MBF reserve early after HTx (group A: 1.82  0.33) and a restoration to normal values thereafter (group B: 2.52  0.53 vs NL: 2.62  0.51, p = ns). Separate analysis of 5 patients studied twice is consistent with these results. Conclusion: This study shows that in heart transplant recipients free of allograft rejection and with normal coronary angiography, MBF reserve is impaired early after HTx. Restoration within one year suggests that this abnormality does not represent an early stage of cardiac allograft vasculopathy. J Heart Lung Transplant 2000;19:538–545. After heart transplantation (HTx), cardiac allo- graft vasculopathy (CAV) is one of the major factors limiting long-term survival. 1,2 It is therefore impor- tant to assess this peculiar form of coronary artery From the Department of Cardiology, a Department of Cardiac Surgery, b and PET/Biomedical Cyclotron Unit, c Erasme Hos- pital, Free University of Brussels, Brussels, Belgium. Submitted December 7, 1999; accepted February 16, 2000. This study was supported by research grant 3.4516 92 F from the Funds for Medical Scientific Research (FRSM, Belgium) and from the “Fondation Pour La Chirurgie Cardiaque” (Brussels, Belgium). Nicolas Preumont is research fellow of the “Fonda- tion Erasme” (Brussels, Belgium). Reprint requests: Nicolas Preumont, MD, Erasme Hospital, Department of Cardiology, Route de Lennik 808, B-1070 Brussels, Belgium, Tel: 32-2-5553907. Fax: 32-2-5554701. Copyright © 2000 by the International Society for Heart and Lung Transplantation. 1053-2498/00/$–see front matter PII S1053-2498(00)00093-0 538