IMIPRAMINE IN PATIENTS WITH CHEST PAIN DESPITE NORMAL CORONARY ANGIOGRAMS

Background. Ten to 30 percent of patients undergoing cardiac catheteri zation because of chest pain are found to have normal coronary angiogr ams. Because these patients may have a Visceral pain syndrome unrelate d to myocardial ischemia, we investigated whether drugs that are usefu l in chronic pain syndromes might also be beneficial in such patients. Methods. Sixty consecutive patients underwent cardiac, esophageal, ps ychiatric, and pain-sensitivity testing and then participated in a ran domized, double-blind, placebo-controlled three-week trial of clonidin e at a dose of 0.1 mg twice daily (20 patients), imipramine at a dose of 50 mg nightly with a morning placebo (20 patients), or placebo twic e daily (20 patients); this treatment phase was compared with an ident ical period of twice-daily placebo for all patients (placebo phase). R esults. Thirteen (22 percent) of the 60 patients had ischemic-appearin g electrocardiographic responses to exercise, 22 of the 54 tested (41 percent) had abnormal esophageal motility, 38 of 60 (63 percent) had o ne or more psychiatric disorders, and 52 of 60 (87 percent) had their characteristic chest pain provoked by right ventricular electrical sti mulation or intracoronary infusion of adenosine. During the treatment phase, the imipramine group had a mean (+/-SD) reduction of 52+/-25 pe rcent in episodes of chest pain, the clonidine group had a reduction o f 39+/-51 percent, and the placebo group a reduction of 1+/-86 percent , all as compared with the placebo phase of the trial. Only the improv ement with imipramine was statistically significant (P = 0.03). Repeat assessment of sensitivity to cardiac pain while the patients were rec eiving treatment showed significant improvement only in the imipramine group (P = 0.01). The response to imipramine did not depend on the re sults of cardiac, esophageal, or psychiatric testing at base line, or on the change in the psychiatric profile during the course of the stud y, which generally improved in all three study groups. Conclusions. Im ipramine improved the symptoms of patients with chest pain and normal coronary angiograms, possibly through a visceral analgesic effect.