The preventive effect of magnesium on coronary spasm in patients with vasospastic angina

Study objectives: Previous studies have reported that magnesium (Mg) defici ency is associated with coronary spasm. However, little is known about the preventive effect of Mg on coronary spasm. The present study investigated w hether Mg prevents coronary spasm in patients with vasospastic angina (VSA) . Design: Effectiveness trial. Setting: University medical center. Patients: Twenty-two patients with VSA. Intervention: Coronary spasm was induced with an intracoronary infusion of acetylcholine (Ach). After spontaneous relief of the coronary spasm, Mg sul fate (0.27 mmol/kg body weight) was infused IV over 20 min in 14 patients a nd isotonic glucose was infused in 8 patients as control subjects. Intracor onary infusion of Ach was then repeated, and the diameter of the coronary a rteries was measured quantitatively. Measurements and results: Mg infusion caused coronary artery dilatation at baseline in both the spastic (5.9 +/- 2.3%) and nonspastic segments (5.5 +/ - 1.5%). Mg infusion reduced the severity of chest pain and ST-segment devi ations during coronary spasm, After the Mg infusion, the percent change in the diameter of the spastic segments improved from - 62.8 +/- 2.6% to - 43. 7 +/- 4.7% during coronary spasm. Overall, 10 of 14 patients (71%) responde d favorably to Mg infusion, Isotonic glucose infusion did not elicit change s in chest pain severity, ST-segment deviations, or the diameter of the cor onary arteries during spasm. Conclusions: Mg infusion produces nonsite-specific basal coronary dilatatio n and suppresses Ach-induced coronary spasm in patients with VSA.