Chest pain is a common reason for hospital admission. In most patients with chest pain, acute coronary artery disease (CAD) is the major concern. Nitrates often are used in emergency treatment of acute chest pain, but relief with nitrates is an uncertain diagnostic and prognostic sign. Because nitro-glycerin can relieve symptoms of noncardiac chest pain, including esophageal spasm, its value as a tool in the diagnosis of ischemic heart disease is questionable. Henrikson and associates conducted a prospective study to determine the usefulness of chest pain response to nitroglycerin as an indicator of ischemic coronary disease.
Patients who had documented chest pain while under medical supervision were given nitroglycerin. A chest pain response to the first dose of nitroglycerin was defined as a 50 percent or greater decrease in pain intensity within five minutes of nitroglycerin administration. The presence of active CAD was determined for all participants. Active CAD was defined as elevated troponin levels, abnormal angiography, a positive stress test, or diagnosis at the time of hospital admission that was confirmed by a study cardiologist. Follow-up telephone calls were made to all participants approximately four months after hospitalization to determine clinical status.
Of the total study sample of 459 patients, 181 patients had relief of chest pain with nitroglycerin. In patients with chest pain that likely was caused by active CAD, 35 percent had pain relief with nitroglycerin. Nitroglycerin also reduced chest pain in 41 percent of the patients without active CAD. Both sensitivity and specificity of chest pain relief by nitroglycerin as a predictor of active CAD were low in the study group as a whole and in the subgroups. Chest pain relief also did not predict outcomes.
The authors conclude that in an emergency setting, chest pain relief with nitro-glycerin lacks diagnostic or prognostic value for acute CAD. These findings possibly could be applied to most outpatient settings.
In an editorial in the same journal, Gibbons questions the external validity of the findings by noting that response to nitroglycerin has different physiologies in patients with acute chest pain and in those with chronic stable angina who have myocardial ischemia. He points out that the evidence supporting the predictive value of response to nitroglycerin in the chronic setting is strong. Gibbons concludes that the study findings may be legitimate in the acute setting, but that nitrate responsiveness is a useful diagnostic and prognostic tool in patients with chronic stable chest pain.