Aims
HER2 directed therapies increase the risk of left ventricular (LV) dysfunction with reported incidence of asymptomatic LV dysfunction and congestive heart failure of ~10-20% and <4%, respectively. We performed a retrospective study in a major tertiary centre in Melbourne, Australia to characterise patterns and outcomes of cardiac toxicity resulting from HER2 directed therapy in patients with breast cancer.
Methods
Patients who completed 5 serial studies for LV assessment (baseline then 3-monthly) during the first 12 months of HER2 directed therapy from 2010-2020 were included. We recorded demographics, cancer history, cardiovascular risk factors and outcomes. LV dysfunction was defined as >10% reduction in LV ejection fraction (LVEF) to LVEF <50%.
Results
Of 518 patients who commenced HER2 directed therapy (trastuzumab +/- pertuzumab) during the study period, 222 (42.9%) completed recommended cardiac surveillance (all were female, median age 53 years, 145 (65%) prior anthracycline). Seventeen (7.7%) patients developed LV dysfunction (16 detected on surveillance; 13 asymptomatic, 4 symptomatic; 11 had \LVEF nadir45-50%, 6 of <45%). Of these, 9 had prior anthracycline chemotherapy and 10 had other cardiovascular risk factors. Thirteen patients had treatment interruption because of cardiac toxicity, 14 patients were referred to a cardiologist, 10 started angiotensin converting enzyme inhibitor treatment and 11, beta blocker therapy. Of these, 7 were successfully rechallenged.
Conclusions
Most patients treated with HER2 directed therapies did not undergo recommended cardiac surveillance in the first year of treatment. Among those that did, only a small proportion of patients developed symptomatic cardiac toxicity. Current surveillance guidelines are resource intensive and more prospective research is needed to determine the optimal cardiac surveillance frequency for these patients.