Predictive impacts of chronic kidney disease and cardiac sympathetic nervous activity on lethal arrhythmic events in chronic heart failure

Background The clinical implications of chronic kidney disease (CKD) and cardiac sympathetic nervous activity (CSNA) regarding lethal arrhythmic events have not yet been fully elucidated in patients with chronic heart failure (CHF). We hypothesized that the combination of CKD and abnormal CSNA, assessed by I-123-metaiodobenzylguanidine (I-123-MIBG) scintigraphy, may provide useful prognostic information for lethal arrhythmic events. Methods We studied 165 consecutive hospitalized CHF patients without dialysis. Cardiac I-123-MIBG scintigraphy was performed in a clinically stable condition, and abnormal CSNA was defined as a late heart-to-mediastinum ratio of <1.6. CKD was defined as an estimated glomerular filtration rate of <60 ml/min/1.73 m(2). We then investigated the incidence of lethal arrhythmic events (sustained ventricular tachyarrhythmia, appropriate implantable cardioverter-defibrillator therapy, or sudden cardiac death). Results During a median follow-up of 5.3 years, lethal arrhythmic events were observed in 40 patients (24.2%). The patients were divided into four groups according to the presence of CKD and CSNA abnormality: non-CKD/normal CSNA (n = 52), CKD/normal CSNA (n = 39), non-CKD/abnormal CSNA (n = 33), and CKD/abnormal CSNA (n = 41). Kaplan-Meier analysis showed that CKD/abnormal CSNA had the highest event rate (log-rank p = .004). Additionally, the Cox proportional hazard analysis revealed that CKD/abnormal CSNA was a predictor for lethal arrhythmic events compared with non-CKD/normal CSNA (hazard ratio, 5.368, p = .001). However, the other two groups did not show significant differences compared with the non-CKD/normal CSNA group. Conclusions The combination of CKD and abnormal CSNA, assessed by I-123-MIBG scintigraphy, had a high predictive value for lethal arrhythmic events in patients with CHF.