HER2-directed therapy is associated with an increased rate of cardiologic emergency department visits in real-world breast cancer patients

BACKGROUND: Subtype is a key prognostic factor for breast cancer. In HER2-positive disease, HER2-directed therapies have improved outcomes, though they can cause cardiac side effects, potentially leading to emergency department (ED) visits. OBJECTIVES: To assesses reasons for ED presentations in breast cancer patients, highlighting subtype-specific differences in reason for presentation, 3-month mortality (3 MM) and the possible association of cardiologic visits with HER2-directed therapy. METHODS: In this retrospective study, visits by breast cancer patients at an Austrian tertiary care ED were analysed. Subtype frequency rates and subtype-specific 3 MM rates were calculated using Chi-Square tests (separately for early and advanced disease). A possible association between HER2-directed therapies and cardiologic ED visits was investigated using a Fisher's exact test and a multinomial logistic regression controlling for age. RESULTS: There was a total of 463 ED visits among 322 patients between August 2016 and December 2019. Subtype distribution was as follows: 42% (n = 135) luminal B-like/HER2-negative, 23% (n = 74) triple negative, 16% (n = 50) luminal B-like/HER2-positive, 10% (n = 33) luminal A-like and 9% (n = 30) HER2-positive (non-luminal). In patients with advanced BC, subtype was significantly associated with 3 MM (p = 0.006), with the highest mortality rate observed in TNBC (54%). Active HER2-directed therapy (n = 70) was associated with increased cardiologic ED visits (OR = 4.536 [95%CI, 1.850- 11.125]). CONCLUSIONS: BC subtype influenced the frequency of ED visits and patient survival. HER2-directed therapy was associated with an increased risk for cardiologic ED visits among real-world cancer patients, emphasizing the need for tailored cardio-oncologic care strategies to optimize tolerability and reduce healthcare burdens.