Use of provocative testing in angina pectoris

Area of Science:

• Cardiology
• Diagnostic Medicine
• Pharmacology

Background:

• Coronary artery spasm is a significant factor in spontaneous angina pectoris.
• Diagnosing spontaneous spasm is challenging due to its rarity.
• Provocation testing offers a controlled method for spasm detection.

Purpose of the Study:

• To evaluate the utility of the methergine provocation test in diagnosing coronary artery spasm.
• To assess the incidence of spasm in various patient groups presenting with chest pain.
• To determine the safety and mechanism of methergine-induced coronary artery spasm.

Main Methods:

• A standard protocol involving a 0.4 mg methergine bolus injection was used.
• 321 patients were studied across five groups based on chest pain presentation.
• Coronary sinus blood flow was measured to understand the underlying mechanism.

Main Results:

• Spasm was induced in 48 of 104 patients with spontaneous angina, particularly Prinzmetal's variant angina.
• Spasm was observed in 7 of 52 patients with angina at rest and effort, and 2 of 24 with myocardial infarction and normal coronary arteries.
• The risk of serious complications was very low when induced spasm was promptly relieved with nitroglycerin.

Conclusions:

• The methergine provocation test is a valuable diagnostic tool for coronary artery spasm.
• The test is indicated for patients with spontaneous angina, especially Prinzmetal's variant angina, and those with angina at rest/effort or myocardial infarction.
• The primary mechanism of spasm involves increased vascular resistance, not increased myocardial oxygen demand.