The terms indigestion includes heartburn along with a number of other symptoms. Indigestion is sometimes defined as a combination of epigastric pain and heartburn. Heartburn is commonly used interchangeably with gastroesophageal reflux disease rather than just to describe a symptom of burning in one's chest.
Heart attack symptoms and esophageal symptoms can be very similar, as the heart and esophagus use the same nerve supply. Because of the dangers inherent in an overlooked diagnosis of heart attack, cardiac disease should be considered first in people with unexplained chest pain. People with chest pain related to GERD are difficult to distinguish from those with chest pain due to cardiac conditions. Each condition can mimic the signs and symptomatic findings of the other. Further medical investigation, such as imaging, is often necessary.
Symptoms of heartburn can be confused with the pain that is a symptom of an acute myocardial infarction (heart attack) or angina. A description of burning or indigestion-like pain increases the risk of acute coronary syndrome, but not to a statistically significant level. In a group of people presenting to a hospital with GERD symptoms, 0.6% may be due to ischemic heart disease.
As many as 30% of chest pain patients undergoing cardiac catheterization have findings which do not account for their chest discomfort, and are often defined as having "atypical chest pain" or chest pain of undetermined origin. According to data recorded in several studies based on ambulatory pH and pressure monitoring, it is estimated that 25% to 50% of these patients have evidence of abnormal GERD.
Gastroesophageal reflux disease is the most common cause of heartburn. In this condition acid reflux has led to inflammation of the esophagus.
Functional heartburn is heartburn of unknown cause. It is associated with other functional gastrointestinal disorder like irritable bowel syndrome and is the primary cause of lack of improvement post treatment with proton pump inhibitors (PPIs). PPIs are however still the primary treatment with response rates in about 50% of people. The diagnosis is one of elimination, based upon the Rome III criteria: 1) burning retrosternal discomfort; 2) elimination of heart attack and GERD as the cause; and 3) no esophageal motility disorders. It was found to be present in 22.3% of Canadians in one survey.