Longer-term assessment of trastuzumab-related cardiac adverse events in the Herceptin Adjuvant (HERA) trial.

Objective: We investigated the incidence of cardiac adverse events in patients with early breast cancer in the Herceptin Adjuvant (HERA) trial who were treated with 1 year of trastuzumab after completion of (neo)adjuvant chemotherapy.

Methods: The HERA trial is a three-group, randomized trial that compared 1 year or 2 years of trastuzumab with observation in women with human epidermal growth factor receptor-2 (HER2) -positive early breast cancer. Eligible patients had normal left ventricular ejection fraction (LVEF; >or= 55%) after completion of (neo)adjuvant chemotherapy with or without radiotherapy. Cardiac function was monitored throughout the trial. This analysis considers patients randomly assigned to 1 year of trastuzumab treatment or observation.

Results: There were 1,698 patients randomly assigned to observation and 1,703 randomly assigned to 1 year of trastuzumab treatment; 94.1% of patients had been treated with anthracyclines. The incidence of discontinuation of trastuzumab because of cardiac disorders was low (5.1%). At a median follow-up of 3.6 years, the incidence of cardiac end points remained low, though it was higher in the trastuzumab group than in the observation group (severe CHF, 0.8% v 0.0%; confirmed significant LVEF decreases, 3.6% v 0.6%) In the trastuzumab group, 59 of 73 patients with a cardiac end point reached acute recovery; of these 59 patients, 52 were considered by the cardiac advisory board (CAB) to have a favorable outcome from the cardiac end point.

Conclusions: The incidence of cardiac end points remains low even after longer-term follow-up. The cumulative incidence of any type of cardiac end point increases during the scheduled treatment period of 1 year, but it remains relatively constant thereafter.