Muser Daniele, Tioni Chiara, Shah Ranjit, Selvanayagam Joseph B, Nucifora Gaetano
Cardiothoracic Department, University Hospital "Santa Maria della Misericordia", Udine, Italy.
Cardiothoracic Department, University Hospital "Santa Maria della Misericordia", Udine, Italy; Postgraduate School of Cardiovascular Sciences, University of Trieste, Trieste, Italy.
Am J Cardiol. 2017 Aug 15;120(4):527-533. doi: 10.1016/j.amjcard.2017.05.019. Epub 2017 May 30.
Postinfarction mechanical dispersion (MD), that is, the regional heterogeneity of myocardial contraction throughout the cardiac cycle, has detrimental effects on left ventricular (LV) function and is related to the occurrence of heart failure and ventricular arrhythmias. However, its prevalence, pathophysiological determinants, and clinical utility are still unknown. The aim of the present study is to clarify these issues. In total, 130 consecutive patients (mean age 60 ± 12 years, 75% male) with a first ST-segment elevation myocardial infarction (STEMI) were included. Cardiac magnetic resonance (CMR) with late gadolinium enhancement imaging was performed to assess LV function, infarct size, and microvascular obstruction. Feature-tracking analysis was applied to cine-CMR short-axis images to assess MD, defined as the SD of the time-to-peak circumferential strain of the LV segments expressed as percent cardiac cycle. For comparison purpose, 40 control subjects similar in age and gender to the STEMI group were also included. Patients were followed-up for a median of 95 months; the outcome event was defined as a composite of cardiovascular death, aborted sudden cardiac death, and hospitalization for heart failure. STEMI patients had significantly higher MD compared with controls (12.0 ± 5.35% vs 3.85 ± 0.99%, p <0.001). At multivariate analysis, heart rate (β = 0.20, p = 0.008), LV end-systolic volume index (β = 0.37, p <0.001), and infarct size (β = 0.23, p = 0.017) were significantly and independently related to MD. The outcome event occurred in 26 (20%) patients. At multivariate Cox proportional hazards analysis, MD was significantly and independently related to the outcome event (p <0.001). MD provided significant incremental value over the other clinical and CMR variables in predicting the outcome event (p <0.001 for the chi-square change). In conclusion, MD after STEMI is a marker of the extent of myocardial damage; its assessment by feature-tracking CMR provides significant, independent, and incremental long-term prognostic information.
梗死后机械离散（MD），即整个心动周期中心肌收缩的区域异质性，对左心室（LV）功能有不利影响，并与心力衰竭和室性心律失常的发生有关。然而，其患病率、病理生理决定因素和临床效用仍不清楚。本研究的目的是阐明这些问题。总共纳入了130例连续的首次ST段抬高型心肌梗死（STEMI）患者（平均年龄60±12岁，75%为男性）。进行了钆延迟增强成像的心脏磁共振（CMR）检查，以评估左心室功能、梗死面积和微血管阻塞情况。将特征追踪分析应用于CMR电影短轴图像，以评估MD，MD定义为左心室节段圆周应变达峰时间的标准差，以心动周期百分比表示。为作比较，还纳入了40名年龄和性别与STEMI组相似的对照受试者。对患者进行了中位时间为95个月的随访；结局事件定义为心血管死亡、心脏性猝死未遂和因心力衰竭住院的复合事件。STEMI患者的MD显著高于对照组（12.0±5.35%对3.85±0.99%，p<0.001）。在多变量分析中，心率（β=0.20，p=0.008）、左心室收缩末期容积指数（β=0.37，p<0.001）和梗死面积（β=0.23，p=0.017）与MD显著且独立相关。26例（20%）患者发生了结局事件。在多变量Cox比例风险分析中，MD与结局事件显著且独立相关（p<0.001）。在预测结局事件方面，MD比其他临床和CMR变量具有显著的增量价值（卡方变化p<0.001）。总之，STEMI后的MD是心肌损伤程度的标志物；通过特征追踪CMR对其进行评估可提供显著、独立且具有增量价值的长期预后信息。
