METAIODOBENZYLGUANIDINE AND HEART-RATE-VARIABILITY IN HEART-FAILURE

It is assumed that the low-frequency power (LF) of heart rate variabil ity (HRV) increases with progress of congestive heart failure (CHF), t herefore positively correlating with cardiac I-123-metaiodobenzylguani dine (MIBG) washout. It is demonstrated here that HRV, including norma lized LF, correlated inversely with MIBG washout and positively with t he ratio of heart-to-mediastinum MIBG activity in controls and CHF pat ients, whereas these correlations were not observed within CHF patient s. Thus MIBG washout may increase and HRV including normalized LF may decrease with CHF, although the HRV and MIBG measures may not similarl y change in proportion to the severity of the cardiac autonomic dysfun ction in CHF.