45-year-old woman who suffered a cardiopulmonary arrest while at work. She had extensive workup and the cause of her arrest was thought to be associated with probable myocarditis. She underwent subsequent ICD implantation. Initially she had severe LV dysfunction (EF 15%). A full evaluation was done that time, and no significant coronary artery disease or persistent cardiomyopathy was identified. Now, 15 years later, she is diagnosed with left-sided IDC, G2, TNBC. Clinically tumor size < 2cm and node negative (cT1N0). She was unable to get breast MRI due to AICD. She was deemed not to be a candidate for neoadjuvant chemo-immunotherapy due to her comorbidities and hence underwent left mastectomy and ALND (pT2N1a, tumor 2.2 cm; 3/12 LNs positive with one measuring 4.2cm and +ENE). Initial plan was to start adjuvant adriamycin and cyclophosphamide given every 2 weeks for 4 cycles followed by Taxol given every 2 weeks for 4 cycles (AC-T regimen). After multiple discussions and based on patient preference, regimen was changed to weekly carboplatin and weekly taxol. Plan is for adjuvant RT after chemotherapy is completed given large node and ENE. We are considering introducing pembrolizumab (her PD-L1 (22C3) CPS is 40) but are concerned about her history of myocarditis. Her most recent echo from this month showed LV EF of 46%, with a severely dilated left atrial cavity. RV size and function are normal. Of note, she also has PALB2 mutation. So perhaps a PARPi could be a (better) option? Wondering what your thoughts would be regarding adjuvant pembrolizumab vs PARPi.