左心室射出分率是目前最廣為使用來評估左心室收縮功能的測量標的，也是各個治療指引常使用的測量標的。然而左心室射出分率有許多缺點，包含了偵測早期收縮功能變化的能力不佳，對於區域性的收縮功能變化無法定量以及在技術上也有諸多限制，例如影像再現性(reproducibility)的困難，容易受到形態學及操作者的影響。最新發展的斑點追蹤心臟超音波(speckle tracking echocardiography)所測量的整體縱向應變(global longitudinal strain) 對於收縮功能的早期變化敏感性很高，而且也能減少形態學變化所帶來的誤差。同時也可以定量區域性的收縮功能變化，對於臨床上判斷特定的疾病，或是疾病進程，有很大的效用，比射出分率有更好的能力來預測病患的預後。

The left ventricular ejection fraction (LVEF) is the principal method and commonly used echocardiographic assessment of left ventricular systolic function. Although LVEF has broad applications, it also has some limitations. Measurement of LV systolic function by two-dimensional echocardiography is highly operator-dependent and has less reproducibility. Geometry is also a confounder to affect the measurement. The most important limitation is the insensitivity to detect the early dysfunction. Global longitudinal strain from speckle tracking echocardiography overcomes many limitations. It resolves the reproducibility issues for serial follow up and reduces the deviation from geometric confounders. Moreover, it can quantify the regional variety which can differentiate different pathology of the remodeled hearts. The most impressive evolution is early detection of LV dysfunction even in the subclinical stage. This review introduces this novel echocardiographic assessment of left ventricular systolic function and its clinical applications.