Abstract 375: Cardiac I-123 Metaiodobenzylguanidine Imaging as a Predictor of Cardiac Death in Patients With Mild to Moderate Chronic Heart Failure: A Prospective Long-Term Comparative Study With Heart Rate Turbulence
Background: It is of clinical importance to identify patients with chronic heart failure (CHF) at risk for cardiac death. Cardiac iodine-123 metaiodobenzylguanidine (MIBG) imaging and heart rate turbulence (HRT) analysis provide prognostic information of CHF patients. However, there is no information available on the comparison of prognostic values between MIBG imaging and HRT analysis in CHF patients.
Method: We prospectively followed up 52 CHF outpatients (NYHA 2.0±0.5) with radionuclide LVEF<40% (29±8%). We performed the cardiac MIBG imaging and 24-hour Holter monitoring at entry. The cardiac MIBG heart to mediastinum ratio was measured from the chest anterior view images obtained at 20 and 200 min after isotope injection, and washout rate(WR) was calculated. Abnormal WR was defined as WR≥27%. Furthermore, we calculated HRT from Holter monitoring. Turbulence onset (TO) and turbulence slope (TS) were calculated as HRT parameters. Abnormal values of HRT analysis were defined as TO ≥0 % and TS ≤2.5 ms/beat.
Results: During a follow-up period of 6.6±3.5 (0.2–11.9) years, 17 of 52 patients had cardiac death (sudden cardiac death (SCD) in 11 patients). At Cox analysis, WR was significantly associated with cardiac death (HR 1.055 [95%CI] 1.023 to 1.089) and SCD (1.049 [95%CI] 1.012 to 1.087), while TO and TS had no association with cardiac death and SCD. Cardiac death and SCD were significantly more frequently observed in patients with abnormal WR (cardiac death:56% vs 8%, p=0.0001, SCD:33% vs 8%, p=0.025), although there was no significant difference in the incidence of cardiac death and SCD between patients with normal and abnormal HRT results. Risk ratio of cardiac death and SCD in patients with abnormal WR was 6.9 (95%CI 1.8 to 27.4) and 4.2 (95%CI 1.0 to 17.5), respectively.
Conclusion: Cardiac MIBG imaging could provide powerful prognostic information in patients with mild to moderate CHF, while HRT analysis could not.