Abstract 12148: Superiority of the Prognostic Value of Cardiac I-123 Metaiodobenzylguanidine Imaging to Heart Rate Recovery Testing in Patients with Chronic Heart Failure

Abstract

Background: Cardiac metaiodobenzylguanidine (MIBG) imaging, which reflects cardiac adrenergic nerve activity, provides prognostic information in chronic heart failure (CHF) patients. Heart rate recovery (HRR) after exercise is related to autonomic function and reported to the prognostic marker in cardiovascular diseases. We sought to prospectively compare the prognostic value of cardiac MIBG imaging with that of HRR in CHF patients.

Methods and Results: We studied 87 CHF patients with sinus rhythm and radionuclide left ventricular ejection fraction <40% (30±8%). The cardiac MIBG wash out rate (WR) were calculated from the chest anterior view images obtained at 20 and 200 min after isotope injection. Abnormal WR was defined as WR >27%. HRR was defined as the difference in heart rate between at peak exercise and at one minute later after stopping exercise; a value <18 bpm was considered abnormal. During the follow-up period of 7.9±4.1 years, 36 of 87 (41%) CHF patients had the primary endpoint (sudden cardiac death in 11 and hospitalization for worsening heart failure in 25 patients). Patients with the cardiac event had a significant higher WR (35.1±12.7% vs 24.2±13.1% p=0.0002) than those without cardiac events, while HRR was lower in patients with than without the cardiac event(12.3±6.8 vs 14.2±9.8 bpm), although the difference was not statistically significant. Kaplan-Meier analysis revealed that cardiac events were significantly more frequently observed in patients with than without abnormal WR (60% vs 22%, p<0.0001) and in patients with than without abnormal HRR (45% vs 32%, p=0.039). At univarate Cox analysis, both of abnormal WR (p=0.0001) and HRR (p=0.045) were significantly associated with cardiac events. At multivariate Cox analysis, abnormal WR was the only significantly and independently associated with cardiac events (hazard ratio 4.101[95%CI 1.639-10.262, p=0.0026]).

Conclusion: Cardiac MIBG imaging would be more useful to predict the risk of cardiac event in patients with CHF than heart rate recovery testing.