A 50 year old man presents with sudden-onset dyspnea for 2 hours. He denies experiencing chest discomfort or pain, but feels rather weak.

His medical history is significant for poorly controlled diabetes for 10 years complicated by grade II retinopathy and peripheral neuropathy, and poorly controlled hypertension for 6 years. His smoking history amounts to 30 pack years.

A screening ECG performed 6 months ago was normal.