Introduction
Cardiotoxicity, defined by a left ventricular ejection fraction (LVEF) reduction, is a well-documented side effect of chemotherapeutic treatment regimens, in particular when anthracycline (ANT) agents are used [1]. Echocardiography has been proven to be a useful tool in evaluating the systolic function by LVEF among patients with cancer [2]. However, using standard echocardiography alone as a measurement for overall function is not a sensitive tool for detecting subclinical changes that occur before the development of significant irreversible myocardial damage [3]. Therefore, the need for early myocardial injury detection has become critical in managing patients treated with cancer therapy. Recently, the use of 2D speckle-tracking echocardiography, specifically assessment of Global longitudinal strain (GLS), as a measurement of subtle changes in left ventricular systolic function, has been shown to be associated with early diagnosis of cardiotoxicity [4, 5]. Furthermore, both systolic and diastolic function is essential for normal cardiac function [6]. Diastolic dysfunction development is considered common among patients with cancer [7], however, no clear evidence has shown that it can predict future systolic dysfunction and its relationship to early signs of cardiotoxicity is limited. Currently, diastolic function is evaluated by a number of parameters including e’, E/e’ ratio, E/A ratio, deceleration time (DT) and left atrium volume index (LAVI) [8, 9, 10], however, these conventional measurements do not assess the direct relaxation of LV and have limitations (e.g. angle dependency) [11]. Strain imaging for the evaluation of diastolic function, using global diastolic strain rate (Dsr), has been shown to have prognostic information regarding cardiovascular morbidity and mortality [12]. Moreover, Dsr has been used in predicting outcomes in cohorts with heart failure and acute myocardial infarction, strengthening evidence of its clinical relevance in these specific populations [13, 14]. However, the use of longitudinal diastolic strain time (Dst), measuring the time of lengthening of the myocardium and specifically the change in Dst during cancer therapies has not been documented yet.
The aim of this study was to evaluate the correlation of Dst with the routine echocardiography diastolic parameters and to estimate the role of Dst change for early detection of cardiotoxicity in a breast cancer patients.