Study objectives: Previous studies have reported that
magnesium (Mg) deficiency is associated with coronary spasm. However,
little is known about the preventive effect of Mg on coronary spasm.
The present study investigated whether Mg prevents coronary spasm in
patients with vasospastic angina (VSA).
Setting: University medical
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 sulfate (0.27 mmol/kg body weight) was
infused IV over 20 min in 14 patients and isotonic glucose was infused
in 8 patients as control subjects. Intracoronary infusion of Ach was
then repeated, and the diameter of the coronary arteries was measured
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 deviations 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%) responded favorably to Mg infusion. Isotonic glucose infusion
did not elicit changes in chest pain severity, ST-segment deviations,
or the diameter of the coronary arteries during spasm.
Conclusions: Mg infusion produces nonsite-specific basal
coronary dilatation and suppresses Ach-induced coronary spasm in
patients with VSA.