“…Although the LVEF has been widely used as a tentative marker for severity of heart failure, it has been widely known that there was a lack of connection between the LVEF and peak oxygen uptake [27,28], and that LVEF does not necessarily represent heart failure severity. As well, although the cardiac uptake of metaiodobenzylguanidine (MIBG) has been reported to be positively associated with LVEF, the MIBG uptake was uneven and had no relationship with LVEF in patients with preserved EF [29]. From these data, we assumed that the effects of beta-adrenergic receptor blockers were variable.…”