A 10-year-old child presents with joint pain, low-grade fever, and a history of untreated strep throat 3 weeks ago. The nurse recalls that rheumatic fever is an autoimmune reaction following Group A Streptococcus infection. Which of the following complications should the nurse prioritize monitoring for?

A. Pulmonary hypertension is not a primary complication of rheumatic fever. While pulmonary vascular changes can occur secondary to left-sided heart dysfunction, this is not the main concern in acute rheumatic fever. B. Rheumatic fever is an autoimmune response to Group A Streptococcus. It can involve the heart (carditis), joints (polyarthritis), skin (erythema marginatum), and central nervous system (Sydenham chorea). Cardiac involvement is the most serious complication. Pancarditis may affect the endocardium, myocardium, and pericardium, but valvular damage, especially to the mitral valve, can persist long-term, potentially leading to rheumatic heart disease. Monitoring for heart murmurs, arrhythmias, and signs of heart failure is critical. C. While post-streptococcal glomerulonephritis can follow strep infection, rheumatic fever does not primarily affect the kidneys, and bladder insufficiency is unrelated. D. Coronary artery aneurysms are associated with Kawasaki disease, not rheumatic fever. Hypertension is not a direct feature of rheumatic fever, and coronary involvement is not typical.