Jy. Choi et al., Iodine-123 MIBG imaging before treatment of heart failure with carvedilol to predict improvement of left ventricular function and exercise capacity, J NUCL CARD, 8(1), 2001, pp. 4-9
Background. We examined whether cardiac sympathetic imaging with iodine-123
metaiodobenzylguanidine (MIBG) would predict improvement of left ventricul
ar (LV) function and exercise capacity in patients with heart failure after
treatment with carvedilol.
Methods and Results. Eighteen patients with heart failure and 5 control sub
jects underwent I-123 MIBG imaging. Heart-to-mediastinum ratios at 20 minut
es and 3 hours and myocardial washout rates (WR) were measured. Of the 18 p
atients, 11 were randomized to receive carvedilol medication, whereas the r
emaining 7 received a placebo. Only the carvedilol group demonstrated a sig
nificant improvement in both heart failure functional class and LV ejection
fraction (EF) 1 year after the start of medication. Within the carvedilol
group, MIBG WR showed a significant inverse correlation with improvement in
LVEF (rho = -0.74, P = .02). The diagnostic accuracy of WR for predicting
EF response to carvedilol was 91%. WR also appeared to be inversely related
to the peak oxygen consumption rate (rho = -0.65, P = .08), although this
did not reach statistical significance.
Conclusion. I-123 MIBG imaging appears useful in predicting which patients
with heart failure are likely to show the most improvement in LV function a
nd exercise capacity after carvedilol treatment. Further studies in this ar
ea appear to be warranted.