A 62-year-old woman undergoing chemotherapy for breast cancer presents with a 3-day history of fever and chest pain. Cardiac catheterization reveals a markedly reduced ejection fraction with normal coronary blood flow. A myocardial biopsy is obtained, and a PCR test for coxsackievirus is positive. Histologic examination of this patient’s myocardium will most likely reveal an abundance of which of the followinginflammatory cells?

**Core Concept**
The patient's presentation of fever, chest pain, and reduced ejection fraction with normal coronary blood flow, in the context of a positive PCR test for coxsackievirus, suggests a diagnosis of viral myocarditis. This condition is characterized by inflammation of the heart muscle due to a viral infection.

**Why the Correct Answer is Right**
The inflammation in viral myocarditis is primarily driven by an immune response to the viral infection. In this case, the coxsackievirus is likely the causative agent. The immune response involves the activation of various immune cells, including T cells and macrophages, which infiltrate the heart muscle and contribute to the inflammation. The presence of these immune cells can lead to tissue damage and dysfunction, resulting in the reduced ejection fraction observed in this patient.

**Why Each Wrong Option is Incorrect**
**Option A:** Lymphocytes are indeed involved in the immune response to viral infections, but they are not the most abundant inflammatory cells in viral myocarditis. Monocytes and macrophages play a more prominent role in the inflammatory process.
**Option B:** Neutrophils are typically involved in acute bacterial infections, not viral infections.
**Option C:** Eosinophils are associated with parasitic infections and allergic reactions, not viral myocarditis.

**Clinical Pearl / High-Yield Fact**
Viral myocarditis can be challenging to diagnose, and the presentation can be similar to other cardiac conditions, such as coronary artery disease. A high index of suspicion and a thorough diagnostic workup, including cardiac catheterization and PCR testing, are essential for an accurate diagnosis.

**Correct Answer: C. Monocytes and macrophages.**

✓ Correct Answer: B. Lymphocytes