Leong Darryl P, Hoogslag Georgette E, Piers Sebastiaan R D, Höke Ulas, Thijssen Joep, Marsan Nina Ajmone, Schalij Martin J, Zeppenfeld Katja, Bax Jeroen J, Delgado Victoria
Disciplines of Medicine, Flinders University and the University of Adelaide, Adelaide, Australia; Population Health Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Ontario, Canada.
Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
J Am Soc Echocardiogr. 2015 Apr;28(4):470-7. doi: 10.1016/j.echo.2014.12.012. Epub 2015 Jan 27.
Differences in arrhythmogenic substrate may explain the variable efficacy of implantable cardioverter-defibrillators (ICDs) in primary sudden cardiac death prevention over time after myocardial infarction (MI). Speckle-tracking echocardiography allows the assessment left ventricular (LV) dyssynchrony, which may reflect the electromechanical heterogeneity of myocardial tissue. The aim of the present study was to evaluate the relationship among LV dyssynchrony, age of MI, and their association with the risk for ventricular tachycardia (VT) after MI.
A total of 206 patients (median age, 67 years; 87% men) with prior MIs (median MI age, 6.2 years; interquartile range, 0.66-15 years) who underwent programmed electrical stimulation, speckle-tracking echocardiography, and ICD implantation were retrospectively evaluated. LV dyssynchrony was defined as the standard deviation of time to peak longitudinal systolic strain values using speckle-tracking strain echocardiography. LV scar burden was evaluated by the percentage of segments exhibiting scar (defined as an absolute longitudinal strain of magnitude < 4.5%). Patients were followed up for the occurrence of first monomorphic VT requiring ICD therapy (antitachycardia pacing or shock) for a median of 24 months.
In total, 75 individuals experienced the primary end point of monomorphic VT. LV dyssynchrony was independently associated with the occurrence of VT at follow-up (hazard ratio per 10-msec increase, 1.12; 95% confidence interval, 1.07-1.18; P < .001), together with nonrevascularization of the infarct-related artery and VT inducibility. Patients with older (>180 months) MIs had a higher likelihood of VT inducibility (88% vs 63%, P = .003) and greater scar burden (14.7 ± 15.8% vs 10.7 ± 11.4%, P = .03) compared with patients with recent (<8 months) MIs.
LV dyssynchrony is independently associated with the occurrence of VT after MI.
致心律失常基质的差异可能解释植入式心脏复律除颤器（ICD）在心肌梗死（MI）后预防原发性心脏性猝死的长期疗效差异。斑点追踪超声心动图可用于评估左心室（LV）不同步，这可能反映心肌组织的机电异质性。本研究的目的是评估LV不同步、MI年龄及其与MI后室性心动过速（VT）风险之间的关系。
对206例既往有MI（MI年龄中位数为6.2岁；四分位间距为0.66 - 15岁）且接受程控电刺激、斑点追踪超声心动图检查和ICD植入的患者进行回顾性评估。LV不同步定义为使用斑点追踪应变超声心动图测量的纵向收缩期峰值应变时间的标准差。通过显示瘢痕的节段百分比（定义为绝对纵向应变幅度<4.5%）评估LV瘢痕负荷。对患者进行随访，中位随访时间为24个月，观察首次发生需要ICD治疗（抗心动过速起搏或电击）的单形性VT情况。
共有75例患者达到单形性VT的主要终点。LV不同步与随访期间VT的发生独立相关（每增加10毫秒的风险比为1.12；95%置信区间为1.07 - 1.18；P <.001），同时与梗死相关动脉未再血管化和VT可诱导性相关。与近期（<8个月）MI的患者相比，MI时间较长（>180个月）的患者VT可诱导性更高（88%对63%，P =.003），瘢痕负荷更大（14.7±15.8%对10.7±11.4%，P =.03）。
LV不同步与MI后VT的发生独立相关。
