OBJECTIVES
This prospective study was undertaken to correlate early and late metaiodobenzylguanidine (MIBG) cardiac uptake with cardiac hemodynamics and exercise capacity in patients with heart failure and to compare their prognostic values with that of peak oxygen uptake (VO2).
BACKGROUND
The cardiac fixation of MIBG reflects presynaptic uptake and is reduced in heart failure. Whether it is related to exercise capacity and has better prognostic value than peak VO2is unknown.
METHODS
Ninety-three patients with heart failure (ejection fraction <45%) were studied with planar MIBG imaging, cardiopulmonary exercise tests and hemodynamics (n = 44). Early (20 min) and late (4 h) MIBG acquisition, as well as their ratio (washout, WO) were determined. Prognostic value was assessed by survival curves (Kaplan–Meier method) and uni- and multivariate Cox analyses.
RESULTS
Late cardiac MIBG uptake was reduced (131 ± 20%, normal values 192 ± 42%) and correlated with ejection fraction (r = 0.49), cardiac index (r = 0.40) and pulmonary wedge pressure (r = −0.35). There was a significant correlation between peak VO2and MIBG uptake (r = 0.41, p < 0.0001). With a mean follow-up of 10 ± 8 months, both late MIBG uptake (p = 0.04) and peak VO2(p < 0.0001) were predictive of death or heart transplantation, but only peak VO2emerged by multivariate analysis. Neither early MIBG uptake nor WO yielded significant insights beyond those provided by late MIBG uptake.
CONCLUSIONS
Metaiodobenzylguanidine uptake has prognostic value in patients with wide ranges of heart failure, but peak VO2remains the most powerful prognostic index.