A 35-year-old man with a history of acute rheumatic fever (ARF) 8 years ago presents for routine follow-up. He is asymptomatic with no dyspnea or chest pain. On auscultation, there is a soft diastolic murmur at the apex. Echocardiography reveals mild mitral regurgitation with normal left ventricular dimensions and ejection fraction of 62%. There is no evidence of mitral stenosis. He has no history of atrial fibrillation. What is the most appropriate next step in management?