Prognostic Impact and Arrhythmic Potential of Peri-infarct Zone by Cardiac MRI

心脏性猝死（SCD）的发生率 心肌梗死（MI）保持不变，并且在MI后的第一年最为显著。的 据报道，在梗塞周围区观察到的显著的细胞各向异性是 室性心律失常心脏磁共振成像（CMR）可以表征心肌 心肌梗死后心肌组织变化和心室功能。最近，我们的团队证明了临床 使用对比增强CMR（PIZCMR）量化梗死周围区范围的可行性， 也报道了其与MI后全因死亡率的强预后相关性。(3)在144项研究中， 对于MI患者，我们使用了一种新的自动化技术来量化晚期增强区域， 基于信号强度阈值（> 3SD和2 - 3 SD）的核心和梗死周围（PIZCMR）区域 分别高于远端正常心肌）。PIZCMR以绝对质量定量 （MDE外围）和总增强区域的百分比（%MDE外围）。我们发现 % MDE外周是全因死亡率随患者年龄增加而增加的强有力预测因子， 心室射血分数（LVEF）。随着数字信号处理的最新进展，微伏T波 交替（MTWA）检测不稳定的电生理底物，使MI后患者暴露于 SCD。在治疗方面，强有力的实验证据表明， ω-3多不饱和脂肪酸（ω-3 FA）对恶性心律失常的作用已得到证实， 大规模随机研究中，冠状动脉疾病患者的SCD显着降低 临床试验这些已发表的研究结果为本提案提供了动力，以阐明 PIZCMR与MI后死亡率之间的预后相关性的致病基础。的 该建议的中心假设是PIZCMR包含结构和电基底 对于折返性室性心动过速的产生至关重要，并且可以通过以下方式促进其愈合： ）-3 FA，转化为SCD和/或需要治疗的严重心室肌无力事件的风险降低。 除颤因此，我们计划将414例急性心肌梗死患者随机分为两组， 或者）-3 FA（4 gm/天，持续9个月）或安慰剂设计用于检验以下假设：1）直接 PIZCMR的心肌定量提供了除LVEF之外的增量预后相关性， MTWA，伴有MACE; 2）口服补充）-3 FA可以有益地改变预后 PIZCMR与MACE的相关性; 3）患有急性MI并有大出血的患者 PIZCMR，通过MTWA表现出伴随的电异质性;和4）口服）-3FA补充， 急性心肌梗死患者，减少PIZCMR的心肌范围并使MTWA正常化， 与安慰剂对照组相比。

The incidence of sudden cardiac death (SCD) after myocardial infarction (MI) has remained unchanged and is most significant in the first year after MI. The marked cellular anisotropy observed in the peri-infarct zone has reported to be a potential cause of ventricular arrhythmias. Cardiac magnetic resonance imaging (CMR) can characterize myocardial tissue changes and ventricular function after MI. Recently, our group demonstrated the clinical feasibility of quantifying the extent of the peri-infarct zone using contrast-enhanced CMR (PIZCMR) and also reported its strong prognostic association with post-MI all-cause mortality.(3) In a study of 144 patients with MI, we used a novel automated technique to quantify the late-enhancing region into the core and peri-infarct (PIZCMR) regions based on signal-intensity threshold (>3SDs and 2 to 3 SDs above remote normal myocardium, respectively). PIZCMR was quantified in absolute mass (MDEperiphery) and as a percentage of the total enhancing region (%MDEperiphery). We found that %MDEperiphery was a powerful predictor of all-cause mortality incremental to patient age and left ventricular ejection fraction (LVEF). With recent advances in digital signal processing, microvolt T-wave alternans (MTWA) in detecting unstable electrophysiological substrate that exposes post-MI patients to SCD. On the therapeutic side, strong experimental evidence of membrane stabilization effects of omega-3 polyunsaturated fatty acids ()-3 FA) against malignant arrhythmias has been substantiated by a remarkable reduction of SCD in patients with coronary artery disease in large-scale randomized clinical trials. These published findings provide the impetus for the present proposal to elucidate the pathogenic basis underlying the observed prognostic association of PIZCMR and post-MI mortality. The central hypothesis of this proposal is that PIZCMR contains the structural and electrical substrate essential for the generation of reentrant ventricular tachycardia, and that its healing can be promoted by )-3 FA, translating to a reduced risk of SCD and/or significant ventricular arrhythmic events requiring defibrillation. Accordingly, we plan to randomized 414 patients with acute MI to supplementation with either )-3 FA (4 gm/day for 9 months) or placebo is designed to test the hypotheses that 1) Direct myocardial quantitation of PIZCMR provides incremental prognostic association, beyond LVEF and MTWA, with MACE; 2) Oral supplementation with )-3 FA can beneficially modify the prognostic association of the PIZCMR with MACE; 3) Patients who suffered an acute MI and have a large PIZCMR, exhibit concomitant electrical heterogeneity by MTWA; and 4) Oral )-3 FA supplementation to patients who suffered an acute MI, reduces the myocardial extent of PIZCMR and normalizes MTWA, compared to the placebo control group.