Despite the expansion of the cardio-oncology field, defining cardiotoxicity to guide therapeutic decisions and impact prognosis is still a work in progress. The most widely recognized diagnosis of cardiotoxicity is based on serial changes in the left ventricular ejection fraction (LVEF). The ESC Position Paper recommends that if LVEF decreases by 10% to a value below the lower limit of normal (considered as an LVEF >50%), angiotensin-converting enzyme inhibitors (or angiotensin receptor blockers) in combination with beta-blockers are recommended to prevent further left ventricular (LV) dysfunction or the development of symptomatic heart failure. However, different LVEF thresholds have been proposed by different authors and guidelines,^, and the 2-dimensional (2D)-echocardiography LVEF depends on loading conditions (fluid status varies significantly in cancer patients), has low sensitivity for detecting small LV function changes, is subject to intra- and interobserver variability and relies on geometrical assumptions. Hence, due to the limited availability of cardiac magnetic resonance imaging, 3D echocardiography is the preferred technique for monitoring cardiotoxicity in oncological patients, and the 3D-LVEF is the method of choice for cardiotoxicity surveillance.

Because any grade of cancer therapy-induced myocardial dysfunction matters, a growing body of literature has explored the role of myocardial deformation analysis in patients receiving cancer therapy for early detection of myocardial damage before LVEF starts declining. Speckle-tracking echocardiography (STE) allows quantitative assessment of global and segmental LV myocardial function by measuring strain in a manner largely independent of angle and ventricular geometry. Compared with 2D-strain, 3D-strain has the advantage of tracking the speckle patterns in any direction and out-of-the imaging plane, offering additional deformation parameters (such as area strain) and a more comprehensive quantitation of LV geometry and function.^,

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