Background:
Cardiac I-123 metaiodobenzylguanidine (MIBG) imaging, which reflects cardiac sympathetic activity, provides prognostic information in patients with chronic heart failure (CHF). On the other hand, elevated blood urea nitrogen to creatinine ratio (BUN/Cr), a surrogate for renal neurohumoral activation, is associated with poor outcome in patients with heart failure. However, there is no information available on the prognostic value of cardiac MIBG imaging in patients with CHF, relating to BUN/Cr.
Methods:
We studied 109 CHF outpatients (NYHA class:2.1±0.6, ischemic origin:52%) with left ventricular ejection fraction <40% (30±8%) in our prospective cohort study. At the enrollment, we measured serum level of BUN and Cr, and performed cardiac MIBG scintigraphy. Elevated BUN/Cr was defined as >20. The cardiac MIBG washout rate (WR) was calculated from the chest anterior view images obtained at 20 and 200 min after isotope injection. Abnormal WR was defined as >27%.
Results:
Forty patients had elevated BUN/Cr, and 55 patients had abnormal WR. During a follow up period of 7.5±4.2 yrs, 36 of 109 patients had cardiac death. At multivariate Cox analysis, WR was significantly independently associated with cardiac death in group with both elevated BUN/Cr (p=0.02) and normal BUN/Cr (p=0.004). Kaplan-Meier analysis showed that patients with abnormal WR had a higher risk of cardiac death than those with normal WR, in group with both elevated BUN/Cr (48%[11/23] vs 6%[1/17], p=0.02, adjusted hazard ratio 11.8[95%CI 1.5-92.2]) and normal BUN/Cr (55%[18/33] vs 17%[6/36], p=0.001, adjusted hazard ratio 4.6[95%CI 1.8-11.6]).
Conclusion:
The cardiac MIBG imaging could predict the risk of cardiac death in CHF, irrespective of BUN/Cr.
Interaction Between Loop Diuretic-Associated Mortality and Blood Urea Nitrogen Concentration in Chronic Heart Failure