Myocardial Oxidative Metabolism in Remote Normal Regions in the Left Ventricles with Remodeling After Myocardial Infarction: Effect of β-Adrenoceptor Blockers

Journal of Nuclear Medicine

Junichiro Hayano¹  Hitomi Narita¹  Hiromichi Miyabe¹  Kazuhiro Yajima¹  Akihiko Iida¹  Genjiro Kimura¹  Kazuyuki Kurokawa¹  Nobuyuki Ohte¹  Sachie Akita¹ 

关键词: acetate;    β-blocker;    myocardial infarction;    PET;    remodeling;   

DOI  :  

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

In patients with myocardial infarction (MI), an expansion of the remote normal regions of the left ventricle is often observed. However, the characteristics of such regions are not fully understood. Thus, we investigated this issue from the standpoint of myocardial oxidative metabolism using 11C-acetate PET. Methods: In 33 patients with recent MI (24 not receiving β-blockers, 9 receiving β-blockers) and 12 age-matched normal control subjects, 11C-acetate dynamic myocardial PET scanning was performed at rest. Time-activity curves of 11C-acetate in 5–7 regions of interest (ROIs) on the midventricular transaxial image in each subject were generated, and the clearance rate constant (Kmono) in each ROI was calculated by monoexponential fitting as an index of myocardial oxidative metabolism. The left ventricular (LV) end-diastolic volume index as an index of LV remodeling and the heart rate · pressure product were obtained in all subjects. Results: The LV end-diastolic volume index was significantly larger in patients with MI without β-blockers than in normal control subjects (101 ± 22.5 vs. 61.6 ± 12.8 mL · m−2; P < 0.001). There was no significant difference in the heart rate · pressure product between the patients with MI without β-blockers and the normal control subjects (8,229 ± 1,503 vs. 8,311 ± 1,311 mm Hg · min−1). The Kmono in remote normal regions was significantly greater in patients with MI without β-blockers even when compared with the highest Kmono on the anteroseptal wall of the left ventricle in normal control subjects (0.078 ± 0.022 vs. 0.065 ± 0.007 min−1; P < 0.01). In contrast, the heart rate · pressure product (6,911 ± 1,135 mm Hg · min−1) and the Kmono (0.054 ± 0.009 min−1) in remote normal regions were significantly less in patients with β-blockers than in those without β-blockers (P < 0.001). No significant difference in the LV end-diastolic volume index was found between the MI patients with and without β-blockers. Multivariate regression analysis showed that β-blockers significantly and directly decreased the Kmono in remote normal regions after adjusting the effect of the heart rate · pressure product, although the prime determinant of the Kmono in such regions was the heart rate · pressure product. Conclusion: Myocardial oxidative metabolism in remote normal regions is accelerated in the left ventricles with remodeling after acute MI. Therapy using β-blockers normalizes the myocardial oxidative metabolism in such regions through the reduction of the heart rate · pressure product and their direct effect on the myocardium.

【 授权许可】

Unknown