Sympathetic reinnervation of cardiac allografts evaluated by 123I-MIBG imaging.
Some heart-transplant patients present with improved heart rate response to exercise and anginal pain suggesting reinnervation of allografts. Studies performed up to 5 y post-transplantation have suggested that reinnervation is a slow process that occurs only after 1 y post-transplantation. The purpose of this study was to evaluate the extent of sympathetic reinnervation in heart-transplant patients and its relation to cardiac function.


METHODS
We performed 123I-metaiodobenzylguanidine (MIBG) studies and rest/exercise radionuclide ventriculography in 31 heart-transplant patients 6 mo to 12 y post-transplantation. Intensity of myocardial MIBG uptake was quantified by a heart-to-mediastinum ratio (HMR), and the regional distribution of MIBG was determined by tomographic studies.


RESULTS
HMR correlated positively with time after transplantation (r = 0.607, P < 0.001). Patients studied from 2 to 12 y post-transplantation had an HMR significantly higher than patients studied before 2 y post-transplantation (1.62 +/- 0.2 versus 1.34 +/- 0.2, P < 0.05). Myocardial MIBG uptake was anterolateral in 16 patients, anterior in 3 and anterolateral and septal in 3. Myocardial MIBG uptake was absent in 9 patients. Vasculopathy developed in 8 patients, and 5 of them (63%) had decreased myocardial MIBG uptake. Peak filling rate was higher in patients studied from 2 to 12 y post-transplantation (2.7 +/- 0.8 end-diastolic volume (EDV)/s versus 2.16 +/- 0.5 EDV/s, P = 0.02).


CONCLUSIONS
Sympathetic reinnervation increases with time after heart transplantation and is seen more frequently after 2 y post-transplantation. Complete reinnervation of the transplanted heart does not occur even up to 12 y post-transplantation. Early vasculopathy may delay the process of sympathetic reinnervation.
Estorch
M
M
Department of Nuclear Medicine, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Campreciós
M
M
Flotats
A
A
Marí
C
C
Bernà
L
L
Catafau
A M
AM
Ballester
M
M
Narula
J
J
Carrió
I
I
D019797:3-Iodobenzylguanidine; D000328:Adult; D000368:Aged; D003627:Data Interpretation, Statistical; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D016027:Heart Transplantation / Q000000981:diagnostic imaging*; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008482:Mediastinum / Q000000981:diagnostic imaging; D008875:Middle Aged; D009416:Nerve Regeneration / Q000502:physiology; D015635:Radionuclide Ventriculography; D019275:Radiopharmaceuticals; D012146:Rest; D013318:Stroke Volume / Q000502:physiology; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging / Q000502:physiology*; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine