Effects of oral magnesium therapy on exercise tolerance, exercise-induced chest pain, and quality of life in patients with coronary artery disease.

Previous studies have demonstrated that magnesium supplementation improves endothelial function in patients with coronary artery disease (CAD). However, the impact on clinical outcomes, such as exercise-induced chest pain, exercise tolerance, and quality of life, has not been established. In a multicenter, multinational, prospective, randomized, double-blind and placebo-controlled trial, 187 patients with CAD (151 men, 36 women; mean +/- SD age 63 +/- 10 years, range 42 to 83) were randomized to receive either oral magnesium 15 mmol twice daily (Magnosolv-Granulat, total magnesium 365 mg provided as magnesium citrate) (n = 94) or placebo (n = 93) for 6 months. Symptom-limited exercise testing (Bruce protocol) and responses given on quality-of-life questionnaires were the outcomes measured. Magnesium therapy significantly increased intracellular magnesium levels ([Mg]i) in a substudy of 106 patients at 6 months compared with placebo (35.5 +/- 3.7 vs 32.6 +/- 2.9 mEq/L, p = 0.0151). Magnesium treatment significantly increased exercise duration time compared with placebo (8.7 +/- 2.1 vs 7.8 +/- 2.9 minutes, p = 0.0075), and lessened exercise-induced chest pain (8% vs 21%, p = 0.0237). Quality-of-life parameters significantly improved in the magnesium group. These findings suggest that oral magnesium supplementation in patients with CAD for 6 months results in a significant improvement in exercise tolerance, exercise-induced chest pain, and quality of life, suggesting a potential mechanism whereby magnesium could beneficially alter outcomes in patients with CAD.