A 34-year-old woman with a history of chronic hypertension and two previous cesarean sections presented with symptoms of preeclampsia and fetal growth restriction in her 35th week of pregnancy. The condition progressed to preterm labor, resulting in an emergency cesarean section. Two weeks postpartum, she developed fever, dyspnea, and joint pain. Investigation revealed cardiomegaly, pulmonary edema, and severe ventricular dysfunction. Laboratory tests confirmed autoimmune markers consistent with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). She was diagnosed with acute myocarditis related to SLE/APS and managed with inotropic support, diuretics and immunosuppression. Left ventricular function improved, and she was discharged with ongoing rheumatologic follow-up. This case highlights the complex interplay between peripartum complications, autoimmune diseases, and cardiac involvement, emphasizing the importance of early diagnosis and multidisciplinary management.