Alpha-adrenergic coronary constriction in effort angina

Area of Science:

• Cardiology
• Pharmacology

Background:

• Exercise-induced ischemia is a hallmark of chronic stable angina.
• The role of alpha-adrenergic coronary tone in modulating ischemia during exercise is not fully understood.

Purpose of the Study:

• To assess the role of alpha-adrenergic coronary tone in exercise-induced ischemia.
• To investigate the effects of alpha-adrenergic blockade on ischemic responses during exercise.

Main Methods:

• 23 patients with chronic stable angina underwent symptom-limited supine exercise tests.
• Intracoronary injections of phentolamine, indoramin, or placebo were administered into the most diseased coronary vessel.
• Exercise tests were repeated after drug or placebo administration to compare ischemic responses.

Main Results:

• Intracoronary alpha-blockade with phentolamine or indoramin led to a less pronounced increase in pulmonary artery wedge pressure during exercise.
• ST-segment depression was significantly reduced after phentolamine administration.
• The ST/HR slope, an indicator of myocardial ischemia, decreased significantly after both phentolamine and indoramin.

Conclusions:

• Alpha-adrenergic coronary tone contributes to exercise-induced ischemia in patients with chronic stable angina.
• Alpha-blockade therapy may be beneficial in managing exertional angina.
• Alpha 2-adrenergic mechanisms appear to play a significant role in inappropriate coronary vasoconstriction during exercise.