['The association between sleep-disordered breathing (SDB) assessed by polysomnography and cardiac sympathetic nerve activity (SNA) assessed by cardiac iodine-123 metaiodobenzylguanidine (123I-MIBG) imaging has not been investigated in patients with chronic heart failure (CHF).', 'We performed cardiac 123I-MIBG scintigraphy and overnight polysomnography in 59 patients with stable CHF. The patients were classified into the 3 groups: 19 with no or mild SDB (NM-SDB, apnea-hypopnea index <15); 21 with central sleep apnea (CSA), and 19 with obstructive sleep apnea (OSA). The cardiac washout rate (WR) of 123I-MIBG was obtained from initial and delayed planar 123I-MIBG images. The WR was higher in patients with CSA (54.2 + or - 11.6%) than in those with OSA (37.9 + or - 8.6%, P < .05) or NM-SDB (40.8 + or - 8.8%, P < .05). The WR correlated positively with central apnea index (rho = 0.40, P = .002). A stepwise multiple regression analysis selected CSA and plasma brain natriuretic peptide levels as independent variables associated with the WR.'] Is washout rate of cardiac iodine-123 metaiodobenzylguanidine high in chronic heart failure patients with central sleep apnea?