Cardiac Iodine-123 Metaiodobenzylguanidine Imaging Predicts Sudden Cardiac Death Independently of Left Ventricular Ejection Fraction in Patients With Chronic Heart Failure and Left Ventricular Systolic Dysfunction: Results From a Comparative Study With Signal-Averaged Electrocardiogram, Heart Rate Variability, and QT Dispersion

Abstract

We prospectively compared the predictive value of cardiac iodine-123 metaiodobenzylguanidine (MIBG) imaging for sudden cardiac death (SCD) with that of the signal-averaged electrocardiogram (SAECG), heart rate variability (HRV), and QT dispersion in patients with chronic heart failure (CHF). Cardiac MIBG imaging predicts prognosis of CHF patients. However, the long-term predictive value of MIBG imaging for SCD in this population remains to be elucidated. At entry, cardiac MIBG imaging, SAECG, 24-h Holter monitoring, and standard 12-lead electrocardiography (ECG) were performed in 106 consecutive stable CHF outpatients with a radionuclide left ventricular ejection fraction (LVEF) <40%. The cardiac MIBG washout rate (WR) was obtained from MIBG imaging. Furthermore, the time and frequency domain HRV parameters were calculated from 24-h Holter recordings, and QT dispersion was measured from the 12-lead ECG. During a follow-up period of 65 +/- 31 months, 18 of 106 patients died suddenly. A multivariate Cox analysis revealed that WR and LVEF were significantly and independently associated with SCD, whereas the SAECG, HRV parameters, or QT dispersion were not. Patients with an abnormal WR (>27%) had a significantly higher risk of SCD (adjusted hazard ratio: 4.79, 95% confidence interval: 1.55 to 14.76). Even when confined to the patients with LVEF >35%, SCD was significantly more frequently observed in the patients with than without an abnormal WR (p = 0.02). Cardiac MIBG WR, but not SAECG, HRV, or QT dispersion, is a powerful predictor of SCD in patients with mild-to-moderate CHF, independently of LVEF.