Trastuzumab has led to a significant improvement in the treatment of both advanced and early breast cancer that over-expresses HER2 receptors. However, it is associated with an important cardiotoxicity that requires a systematic monitoring of left ventricular ejection fraction (LVEF) before and during the treatment. We present our experience with patients who developed trastuzumab-related cardiotoxicity.

To evaluate the incidence and the reversibility of trastuzumab induced cardiotoxicity (TIC) in our cardio-oncology unit.

We conducted a prospective observational study from January 2017 to november 2018 in the cardio-oncology unit of Casablanca, Morocco.

In total, 973 patients were included. The average LVEF before initiation of trastuzumab was 59.9±11.2% and 51.9±6.6% at the end of treatment. A decreased LVEF was detected in 38 patients (3.9%), symptomatic in 20 cases, asymptomatic in 18 patients. TIC occured for a mean cumulative dose>40mg/m². During the follow-up, 32 patients (84.2%) had a retrieval of their LVEF after a mean period of 6.4 months after trastuzumab termination. 6 cases of TIC were irreversible despite an optimal cardioprotective therapy.

Patients who develop TIC generally improve their LVEF on removal of the agent and after initiation of cardioprotective therapy. The clinical outcome is more favorable than anthracycline cardiotoxicity. This reversibility is usually observed in early identified patients, showing the importance of a systematic monitoring of LV function before, during and after the treatment.