Abstract 18782: Ejection Fraction Improvement by Beta-Blocker Treatment in Patients with Heart Failure: Relation to Cardiac I-123 meta-iodobenzylguanidine Changes
Background: Reduced myocardial I-123 meta-iodobenzylguanidine (mIBG) uptake has been demonstrated to be an independent predictor of adverse long-term outcome in single-center and multicenter trials. Beta-blocker therapy can improve cardiac function and mIBG parameters. However, there are no reports if the early changes in systolic function after beta-blocker initiation are concurrent with cardiac adrenergic changes as detected by mIBG.
Methods: We prospectively studied 28 HF outpatients (NYHA class II or III) with radionuclide left ventricular ejection fraction less than 40% (27 ± 8%) that never used beta-blockers. The cardiac mIBG imaging was performed at the entry and after 3 and 12 months of beta-blocker therapy (carvedilol). The cardiac mIBG heart to mediastinum ratio (H/M ratio) and washout rate (WR) were calculated from the chest anterior view images obtained at 20 and 240 min after isotope injection.
Results: Mean EF was 28%±10, 32%±12 and 44%±12 at baseline, 3 and 12 months respectively (p<0.05). The 30 minutes and 4 hours H/M ratio improved from 1.61±0.19 and 1.53±0.17 at baseline to 1.92±0.19 and 1.91±0.18 at 12months (p<0,05), but do not had any significant improvement at 3 months (1.7±0.18 and 1.67±0.16, respectively). Washout rate demonstrated a significant improvement only at 12 months of follow-up (32% at baseline, 34% at 3 months and 27% at 12 months (p<0,05).
Conclusion: In heart failure patients, systolic function and adrenergic innervation still show significant changes 1 year after beta-blocker initiation. Systolic function improvement occurs before cardiac mIBG changes. These findings suggest that the left ventricular function recovery is what determines the cardiac autonomic changes observed with beta-blocker therapy and not the opposite.
- © 2010 by American Heart Association, Inc.