Description: a mood disorder characterized by sadness, apathy, irritability, and often accompanied by reduced appetite and weight loss, poor sleeping habits, reduced mentation, and physical sluggishness.

Some causes related to cardiovascular disease: Depression is an extremely common but poorly recognized condition in patients with cardiac disease.  It is especially common following myocardial infarction or cardiac surgery, affecting up to 30% of patients. 

Some causes related to other disorders: Depression is also common with a variety of other medical problems, including cancer, diabetes, neurologic disorders (including, prominently, stroke) and thyroid disorders.

Significance: Patients with cardiac disease who also have depression have a significantly reduced survival.  Patients with the symptoms listed above should be specifically evaluated for depression, a condition that is often missed (especially by cardiologists).  If recognized, depression is readily treatable; if missed, it can lead to early death.