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Imipramine in patients with chest pain despite normal coronary angiograms
R O Cannon1, A A Quyyumi, R Mincemoyer
1Cardiology Branch, National Heart, Lung, and Blood Institute; National Institutes of Health, Bethesda, Md 20892.
Insights
Imipramine significantly reduced chest pain episodes in patients with normal coronary angiograms, suggesting a visceral analgesic effect for this common condition.
Area of Science:
- Cardiology
- Pain Management
- Psychiatry
Background:
- Many patients with chest pain have normal coronary angiograms.
- These patients may experience visceral pain syndrome, not related to myocardial ischemia.
- Investigated potential benefits of chronic pain medications for these patients.
Purpose of the Study:
- To investigate the efficacy of clonidine and imipramine in patients with chest pain and normal coronary angiograms.
- To determine if drugs used for chronic pain syndromes could alleviate symptoms in this patient group.
Main Methods:
- Sixty patients underwent cardiac, esophageal, psychiatric, and pain-sensitivity testing.
- A randomized, double-blind, placebo-controlled trial compared clonidine, imipramine, and placebo over three weeks.
- Treatment efficacy was compared against an identical placebo phase for all patients.
Main Results:
- Imipramine significantly reduced chest pain episodes by 52% compared to placebo (P=0.03).
- Clonidine showed a 39% reduction, while placebo showed a 1% reduction.
- Imipramine also significantly improved sensitivity to cardiac pain (P=0.01).
Conclusions:
- Imipramine effectively improved chest pain symptoms in patients with normal coronary angiograms.
- The therapeutic effect of imipramine may be attributed to its visceral analgesic properties.
Background:
Ten to 30 percent of patients undergoing cardiac catheterization because of chest pain are found to have normal coronary angiograms. Because these patients may have a visceral pain syndrome unrelated to myocardial ischemia, we investigated whether drugs that are useful in chronic pain syndromes might also be beneficial in such patients.
Methods:
Sixty consecutive patients underwent cardiac, esophageal, psychiatric, and pain-sensitivity testing and then participated in a randomized, double-blind, placebo-controlled three-week trial of clonidine 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 twice daily (20 patients); this treatment phase was compared with an identical period of twice-daily placebo for all patients (placebo phase).
Results:
Thirteen (22 percent) of the 60 patients had ischemic-appearing electrocardiographic responses to exercise, 22 of the 54 tested (41 percent) had abnormal esophageal motility, 38 of 60 (63 percent) had one or more psychiatric disorders, and 52 of 60 (87 percent) had their characteristic chest pain provoked by right ventricular electrical stimulation or intracoronary infusion of adenosine. During the treatment phase, the imipramine group had a mean (+/- SD) reduction of 52 +/- 25 percent in episodes of chest pain, the clonidine group had a reduction of 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 improvement with imipramine was statistically significant (P = 0.03). Repeat assessment of sensitivity to cardiac pain while the patients were receiving treatment showed significant improvement only in the imipramine group (P = 0.01). The response to imipramine did not depend on the results of cardiac, esophageal, or psychiatric testing at base line, or on the change in the psychiatric profile during the course of the study, which generally improved in all three study groups.
Conclusions:
Imipramine improved the symptoms of patients with chest pain and normal coronary angiograms, possibly through a visceral analgesic effect.