Overview of diagnostic testing for chest pain of unknown origin

Identifying the cause of recurrent chest pain may be difficult. Significant coronary artery disease must be excluded before patients can be assured that their symptoms are truly "noncardiac." A normal coronary angiogram is the most definitive test but this may not preclude the presence of a new "fly in the ointment," i.e., microvascular angina. Musculoskeletal pain syndromes, psychological problems, and esophageal disorders, including both esophageal motility disorders and gastroesophageal reflux disease, are the most common causes of noncardiac chest pain. Nearly 30% of these patients will have an esophageal motility disorder, although its clinical relevance in the asymptomatic patient is controversial. Simple, inexpensive, provocation tests (most commonly edrophonium, bethanechol, and/or balloon distention) have been developed to recreate motility-related chest pain in the laboratory. These tests can identify the esophagus as the source of pain, but in most cases they do not direct therapy. Other disadvantages of provocation tests include the lack of a gold standard reference point, side effects, and the need for placebo because of a subjective end point. Recently, ambulatory esophageal pH and pressure monitoring have been used to define precisely the cause of esophageal chest pain. These systems can record multiple episodes of pain for up to 24 hours in an outpatient setting and have shown that gastroesophageal reflux (rather than motility disorders) is the most common esophageal cause of pain. However, these studies also suggest that many episodes of chest pain do not have an identifiable esophageal cause. Furthermore, this equipment is expensive, uncomfortable, may alter normal activity, and is not useful in patients having infrequent pain episodes. Psychological disturbances should be carefully sought in any patient with noncardiac chest pain: Many patients have anxiety, depression, or panic attacks that may complicate or contribute to their reported symptoms. It is questionable if these patients need additional testing. Rather, the challenge of the future is to prove that the multitude of tests aid in the overall treatment and outcome of patients with noncardiac chest pain.