A 38-year-old woman presents with dyspnea, pedal edema, and elevated cardiac biomarkers. What is the most likely diagnosis?

The symptoms presented by the 38-year-old woman—dyspnea (difficulty breathing), pedal edema (swelling of the feet), and elevated cardiac biomarkers—point towards myocarditis as the most likely diagnosis.

Myocarditis is inflammation of the heart muscle, which can lead to a reduction in the heart's ability to pump blood effectively. This condition can result from infectious agents, autoimmune reactions, or other factors. The combination of respiratory distress (dyspnea), fluid retention (pedal edema), and elevated cardiac biomarkers, which indicate myocardial injury, aligns well with the pathophysiology of myocarditis.

In cases of myocarditis, patients may develop heart failure symptoms due to impaired cardiac function, which explains the dyspnea and pedal edema. The elevated cardiac biomarkers further support the diagnosis, as they reflect damage to the heart muscle itself.

Other potential options such as endocarditis, myocardial infarction, and pneumonia could present with overlapping symptoms, but they usually yield different clinical findings and would not typically explain the combination of symptoms observed as coherently as myocarditis does in this context.