Dobutamine myocardial scintigraphy for the prediction of cardiac events after heart transplantation.
BACKGROUND
The long-term outcome after heart transplantation (HTx) is essentially influenced by the occurrence and extent of cardiac allograft vasculopathy (CAV). Single photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI) has been shown to be a useful and cost-effective non-invasive method in patients with known or suspected coronary artery disease, but its role in detecting CAV remains unclear.


OBJECTIVE
To evaluate the accuracy and predictive value of dobutamine MPI in patients after HTx during a 12-month follow-up.


METHODS
Seventy-seven patients (60 males, 17 females) underwent a total of 216 dobutamine MPI examinations over a period of 5 years. Examinations were obtained an average of 89+/-42 months after orthotopic HTx according to a 1-day protocol using 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) with and without attenuation correction. For the present study, findings from 77 MPI examinations (one MPI examination per patient) were analysed visually and semiquantitatively using a 20-segment model. Summed stress scores (SSS) and summed rest scores (SRS) were calculated and receiver operating characteristic (ROC) analysis was performed to detect optimum threshold values. Patients were followed up for 12 months and cardiac events were registered.


RESULTS
Cardiac events were observed in 10 of the 77 patients. Good interobserver agreement was found for global visual and SRS-/SSS-based analysis (kappa=0.74 and 0.66, respectively). SSS was superior to SRS in the detection of cardiac events. ROC analysis showed an optimized SSS threshold value of three. For predicting a cardiac event during the 12-month follow-up, global visual and semiquantitative analysis reached sensitivities of 90% and 90%, specificities of 72% and 88%, accuracies of 74% and 87%, positive predictive values of 32% and 53% and negative predictive values of 98% and 98%, respectively. The sensitivity, specificity, accuracy and positive and negative predictive values for MPI to detect clinically relevant coronary artery stenoses (> or =50%) at conventional coronary angiography were 83%, 87%, 86%, 56% and 96%, respectively.


CONCLUSIONS
Non-invasive dobutamine MPI reliably identifies patients at risk for subsequent cardiac events in cases of CAV, with a high negative predictive value of 98% and an accuracy of 87%.
Hacker
Marcus
M
Department of Nuclear Medicine, University of Munich, Munich, Germany. marcus.hacker@med.uni-muenchen.de
Tausig
Andreas
A
Romüller
Bernd
B
Hoyer
Xaver
X
Klauss
Volker
V
Stempfle
Ulrich
U
Reichart
Bruno
B
Hahn
Klaus
K
Tiling
Reinhold
R
D003327:Coronary Disease / Q000000981:diagnostic imaging* / Q000209:etiology*; D004280:Dobutamine; D005080:Exercise Test / Q000379:methods; D005260:Female; D016027:Heart Transplantation / Q000009:adverse effects* / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi
D019275:Radiopharmaceuticals; D004280:Dobutamine; D017256:Technetium Tc 99m Sestamibi