Abstract 3028: Preserved Cardiac Sympathetic Nerve Innervation Contributes to Left Ventricular Reverse Remodeling After Acute Myocardial Infarction: Analysis by MIBG Imaging
Purpose: The left ventricular(LV) remodeling process, beginning soon after the onset of acute myocardial infarction(AMI) and lasting over the year, leads to progressive ventricular enlargement and dysfunction, which associates with very bad prognosis of patients with AMI. And many studies have focused on the determinants of LV remodeling after AMI, it has been implied that the cardiac sympathetic nervous system may play an important role in this process. On the other hand, although left ventricular enlargement and dysfunction has present in acute phase after AMI, there are many patients, whose LV function has improve and LV dimension has reduce at chronic phase; reverse remodeling. But the determinant factor of reverse remodeling process has not fully investigated. So we used I(123)-MIBG imaging, to investigate whether cardiac sympathetic nerve function could contribute to this processes.
Methods: We studied consecutive 44 patients with AMI who received reperfusion therapy at our hospital. We underwent sequential Tc(99m)-myocardial ECG-gated SPECT at acute and chronic phase, and I(123)-MIBG imaging at chronic phase. From the LV diastolic volume (EDV) change between acute and chronic phase, we divided patients into 2 groups; Reverse remodeling group(N=23, EDV decreased>10%)and Unchanged or remodeling group(N=21, EDV decreased ≤ 10% or EDV increased).
Results: There were not any differences in baseline characteristics among both groups. Perfusion defect score among both groups at acute phase (16.2±12.3 vs. 22.2±16.4, respectively P<0.18) and also at chronic phase (15.4±10.8 vs. 19.9±11.4, respectively P<0.19) were similar. By contrast, Reverse remodeling group associated with significantly lower defect score (22.7±14.6 vs. 32.3±14.7, P<0.03) and severity score(2.8±0.90 vs. 3.48±0.81, P<0.01) of MIBG than that of another group. And defect score of MIBG correlates well to LVEF(R=−0.60 P<0.0001) than perfusion defect score(R=−0.54 P<0.001) at chronic phase.
Conclusions: Most of patients with reverse LV remodeling exhibited preserved sympathetic nervous integrity. Therefore preserved cardiac sympathetic nerve innervation (including reinnervation) may play an important role in reverse remodeling processes after AMI.