[Plasma beta-endorphin levels in silent or symptomatic myocardial ischemia]

The role of increased beta-endorphin activity in patients with silent myocardial ischemia has been postulated. To further investigate this hypothesis, 13 patients with silent myocardial ischemia (A) and 10 patients with exercise-induced angina (B) were studied. To be entered in groups A and B patients had to fulfill the following criteria: occurrence or not of anginal pain, according to history and clinical data, during a positive exercise ECG and associated imaging of reversible perfusion defect at thallium-201 scintigraphy. Basal plasma beta-endorphin levels showed significantly (p less than 0.05) higher values in group A as compared to group B. At the end of an exercise stress test, plasma beta-endorphin levels were measured in 9 patients from group A and in 7 from group B. Post-exercise beta-endorphin levels showed a mild increase in group A, but increased significantly in group B (p less than 0.02). The patients with silent or symptomatic myocardial ischemia were quite well-matched with regard to age, sex, number and localization of obstructed coronary vessels, positive exercise ECG and imaging of reversible perfusion defect at thallium-201 scintigraphy. The higher basal plasma beta-endorphin levels in patients with painless ischemia, compared to symptomatic patients, suggested that endogenous opioid peptides play a role in the perception of anginal pain during myocardial ischemia. The fact that post-exercise plasma beta-endorphin levels increased in symptomatic patients but remained unchanged in patients with silent myocardial ischemia does not lead to conclusive considerations.