Abstract 19411: Cardiac β-adrenergic Receptor Density and Myocardial Systolic Function in Patients with Prior Myocardial Infarction and Left Ventricular Remodeling
Left ventricular (LV) remodeling is observed in the remote normal region in the LVs after myocardial infarction (MI) and is closely involved in systolic heart failure. Accordingly, we assessed cardiac β-adrenergic receptor density (Bmax) in 15 patients with a prior myocardial infarction (MI), especially focused on the remote normal region, in comparison with that in 10 age-matched normal controls.
Methods: Cardiac β-adrenergic receptor imaging was obtained using a positron tracer 11C-(-)-4-((S)-3-tert-butylamino-2-hydroxypropoxy)-1,3-dihydrobenzoimidazol-2-one (CGP12177) as a ligand of β-receptor on the LV wall in the trans-axial image and the Bmax in the regions of interest was calculated with an established graphic method. LV regional systolic function was assessed with the use of peak myocardial strain in the longitudinal direction in the LV wall. LV volumes were also measured.
Results: LV end-diastolic volume index was significantly larger in patients with a prior MI than in normal controls (67.8±16.9 vs 49.0±12.3 ml/m2, p<0.01). The Bmax on the whole LV wall was significantly less in patients with a prior MI than in normal controls (5.8±1.7 vs 9.7±4.1 pmol/ml, p<0.01). The Bmax was significantly less in the remote normal region in patients with a prior MI than in the corresponding area in normal controls (6.8±2.2 vs 9.6±4.6 pmol/ml, p<0.05). Peak systolic myocardial strain was significantly reduced in the remote normal LV wall in patients with a prior MI compared with that in the corresponding wall in normal controls (−15.4±2.3 vs -21.0±3.2%, p<0.001). Peak systolic myocardial strain in the MI wall (−10.1±3.0%) was significantly less compared with the remote normal wall (p<0.01).
Conclusion: Cardiac β-adrenergic receptor down regulation with deterioration of myocardial systolic function is observed in the remote normal region in patients with prior MI. This finding may be one of the causes by which systolic heart failure occurs in patients with prior MI and with LV remodeling.
- © 2010 by American Heart Association, Inc.