Case Study: What is causing this 30-year-old's chest pain?

A PREVIOUSLY healthy 30-year-old man presents with a 24-hour history of left-sided pleuritic chest pain.

The pain is relieved almost completely by sitting forward and is exacerbated by lying flat.

On physical examination he is mildly tachycardic, with a heart rate of 100 beats per minute.

His jugular venous pressure is normal, he is normotensive, and he has a low-grade temperature.

Blood tests taken show a mild elevation of the C-reactive protein, and leukocytosis is identified.

His viral serology returns normal.

An ECG is taken and is shown below (Figure 1