Cardiac events after treatment with trastuzumab

This study investigated the rate and outcome of trastuzumab (Herceptin) associated cardiac (heart) dysfunction in patients after 1 or 2 years of therapy. The study concluded that for patients treated with adjuvant trastuzamab, the occurrence of cardiac events remained low and that these cardiac events were mostly reversible after trastuzumab discontinuation. 

Trastuzumab is a common drug used as an adjuvant therapy (an additional therapy given after a primary treatment, such as surgery) to treat patients with human epidermal growth factor 2 positive (HER2+) breast cancer.

Cardiac events can include heart attack, irregular heartbeat and congestive heart failure (a build up of fluid around the heart preventing it from pumping correctly). Generally, trastuzumab is well tolerated, however cardiac events have been reported.

This study investigated the rate and outcome of trastuzumab-associated cardiac dysfunction in patients after 1 or 2 years of therapy. 1,682 patients were randomly assigned to 1 year of trastuzumab treatment (group 1). 1,673 patients were assigned to 2 years of trastuzumab treatment (group 2). 1,744 patients were assigned to observation only (group 3). Patients underwent cardiac testing at the start of the study and every 3 months for 4 years. After that, cardiac monitoring was performed annually between years 5 and 10.

Cardiac events that lead to discontinuation of trastuzumab occurred in 9.4% of patients in group 2 and 5.2% of patients in group 1.  The occurrence of congestive heart failure was significantly higher for groups 1 and 2 (both at 0.08%) compared to group 3 (0%).

4.1% of group 1 patients and 7.2% of group 2 patients experienced a decrease in the ability of the heart to effectively pump blood. 81.2% of these patients in group 1 and 87.5% of group 2 recovered normal heart function.  

The study concluded that for patients treated with adjuvant trastuzamab, the occurrence of cardiac events remains low and that these cardiac events were mostly reversible after trastuzumab discontinuation.

Some patients originally assigned to the observation only group were switched to trastuzumab at the end of the trial period.