Trastuzumab is an effective recombinant humanized monoclonal antibody used for the treatment of breast cancer that over-expresses HER2 receptors. However, it is associated with an important cardiotoxicity. Systolic dysfunction is more frequently assessed than diastolic dysfunction that usually precedes. The aim of our study was to evaluate whether monitoring the ratio of mitral peak velocity of early filling (E) to early diastolic mitral annular velocity (e’, E/e’ ratio) can help assess the risk of trastuzumab-induced cardiotoxicity (TIC)

We conducted a longitudinal prospective study including all the patients treated with trastuzumab for advanced HER2-positive breast cancer followed in the Casablanca cardio-oncology unit from January 2017 to December 2019. E/e’ ratio on tissue Doppler imaging was calculated in all patients before treatment initiation in order to assess its role for early detection of left ventricular ejection fraction (LVEF) alteration. Echocardiography was then performed every 3 months with E/e’ ratio monitoring.

A total of 1092 patients were included, mean age was 51±12 years (17-83). Mitral inflow pattern was normal in 714 (65,4%), restrictive in 37 patients (3.4%), type 1 diastolic dysfunction was noted in 341 cases (31,2%). Among those patients, 586 (53,7%) were under Trastuzumab and LVEF declined in 72 cases (12.3%). A radio E/e’ >15 was assessed in 38 patients undergoing herceptine (6.4 %), and 12 of them (2.0 % of total) actually had alteration of their LVEF. A weak negative correlation was noted between E/e’ elevation and the lowest LVEF (−0,143; P=0,028).

According to our study, left ventricular diastolic function monitoring on the basis of the E/e’ ratio at baseline and every 3 months after treatment initiation is not significantly associated with LVEF decline and can hardly predict LVEF decline in patients undergoing Trastuzumab therapy.