Stage III Breast Cancer Treatment Complicated by Coronary Thrombosis

What happened, in summary

A 44-year-old woman was diagnosed with Stage III invasive ductal carcinoma of the right breast about 3 months before an unexpected cardiac emergency. The tumor was estrogen- and progesterone-receptor positive, HER2-negative, and had a Ki-67 of 25–30%. Imaging showed no distant metastases. She underwent right mastectomy with removal of an involved intramammary lymph node and then began adjuvant doxorubicin and cyclophosphamide. Five days after her second chemotherapy cycle, she developed chest pain radiating to her left arm. Testing showed a myocardial infarction, and coronary angiography found total thrombotic blockages in two coronary arteries despite no evidence of pre-existing coronary atherosclerosis on her earlier cancer workup. She received intensive antithrombotic treatment, and repeat angiography 5 days later showed complete resolution of the clots and restored blood flow. Doxorubicin and cyclophosphamide were discontinued after the cardiac event. Her breast-cancer treatment continued with paclitaxel, followed by letrozole because the cancer was hormone receptor-positive. About 12 months after the myocardial infarction, she had achieved complete remission. At 44 months of follow-up, she remained in complete oncologic remission, and her heart function had improved close to its pre-event level. She continued letrozole and cardiac medications during follow-up.