MRI Unit, G. Monasterio Foundation/CNR-Regione Toscana, Pisa, Italy.
JACC Cardiovasc Imaging. 2010 Jan;3(1):45-51. doi: 10.1016/j.jcmg.2009.06.016.
The purpose of this study was to assess the association of myocardial salvage by cardiac magnetic resonance (CMR) with left ventricular (LV) remodeling and early ST-segment resolution in patients with acute myocardial infarction (MI).
Experimental studies revealed that MI size is strongly influenced by the extent of the area at risk (AAR), limiting its accuracy as a marker of reperfusion treatment efficacy in acute MI studies. Hence, an index correcting MI size for AAR extent is warranted. T2-weighted CMR and delayed-enhancement CMR, respectively, enable the determination of AAR and MI size, and the myocardial salvage index (MSI) is calculated by correcting MI size for AAR extent. Nevertheless, the clinical value of CMR-derived MSI has not been evaluated yet.
In a prospective cohort of 137 consecutive patients with acutely reperfused ST-segment elevation MI, CMR was performed at 1 week and 4 months. T2-weighted CMR was used to quantify AAR, whereas MI size was detected by delayed-enhancement imaging. MSI was defined as AAR extent minus MI size divided by AAR extent. Adverse LV remodeling was defined as an increase in LV end-systolic volume of >or=15%. The degree of ST-segment resolution 1 h after reperfusion was also calculated.
AAR extent was consistently larger than MI size (32+/-15% of LV vs. 18+/-13% of LV, p<0.0001), yielding an MSI of 0.46+/-0.24. MI size was closely related to AAR extent (r=0.81, p<0.0001). After correction for the main baseline characteristics by multivariate analyses, MSI was a major and independent determinant of adverse LV remodeling (odds ratio: 0.64; 95% confidence interval: 0.49 to 0.84, p=0.001) and was independently associated with early ST-segment resolution (B coefficient=0.61, p<0.0001).
In patients with reperfused ST-segment elevation MI, CMR-derived MSI is independently associated with adverse LV remodeling and early ST-segment resolution, opening new perspectives on its use in studies testing novel reperfusion strategies.
本研究旨在评估心脏磁共振（CMR）评估的心肌挽救与急性心肌梗死（MI）患者的左心室（LV）重构和早期 ST 段分辨率之间的关系。
实验研究表明，MI 大小受危险区（AAR）范围的影响很大，这限制了其作为急性 MI 研究中再灌注治疗效果标志物的准确性。因此，需要校正 AAR 范围的 MI 大小的指数。T2 加权 CMR 和延迟增强 CMR 分别可以确定 AAR 和 MI 大小，并且通过校正 AAR 范围来计算心肌挽救指数（MSI）。然而，尚未评估 CMR 衍生的 MSI 的临床价值。
在连续的 137 例急性再灌注 ST 段抬高 MI 患者的前瞻性队列中，在 1 周和 4 个月时进行 CMR。使用 T2 加权 CMR 来定量 AAR，而通过延迟增强成像来检测 MI 大小。MSI 定义为 AAR 范围减去 MI 大小除以 AAR 范围。LV 不良重构定义为 LV 收缩末期容积增加>或=15％。还计算了再灌注后 1 小时 ST 段分辨率的程度。
AAR 范围始终大于 MI 大小（32+/-15％的 LV 与 18+/-13％的 LV，p<0.0001），MSI 为 0.46+/-0.24。MI 大小与 AAR 范围密切相关（r=0.81，p<0.0001）。通过多元分析校正主要基线特征后，MSI 是不良 LV 重构的主要和独立决定因素（比值比：0.64；95％置信区间：0.49 至 0.84，p=0.001），并且与早期 ST 段分辨率独立相关（B 系数=0.61，p<0.0001）。
在再灌注 ST 段抬高 MI 患者中，CMR 衍生的 MSI 与不良的 LV 重构和早期 ST 段分辨率独立相关，为使用新型再灌注策略的研究提供了新的视角。
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