D-22: Free Communication/Poster – Clinical Exercise Testing: THURSDAY, JUNE 2, 2005 2:00 PM - 5:00 PM ROOM: Ryman C2
Previous studies have demonstrated that in patients with coronary artery disease (CAD) an upward deflection of the heart rate (HR) performance curve can be observed and that this upward deflection and the degree of the deflection is correlated with a diminished stress dependent left ventricular function. Magnesium (Mg) supplementation improves endothelial function, exercise tolerance, and exercise-induced chest pain in patients with (CAD). However, the impact of Mg on HR changes during exercise and myocardial function has not been established.
In a prospective, double-blind controlled clinical trial, 53 male patients with CAD (age 63±10 years), were randomized and received either oral Mg 15 mmol twice daily (Magnosolv-Granulat, total Mg 365 mg provided as Mg citrate) (n = 28) or placebo (n = 25) for 6 months. Maximal oxygen uptake (VO2max; incremental cycle ergometer test), the degree and direction of the deflection of the HR performance curve described as factor k < −0.0 (upward deflection) and the left ventricular end-diastolic/systolic diameter (LVDD/LVSD), ejection fraction (LVEF) analyzed via echocardiography, were the outcomes measured.
Mg therapy compared with placebo significantly increased intracellular Mg levels (32.7±2.5 vs. 35.6±2.1 mEq/L, p < 0.001; 33.1±3.1.9 vs 33.8±2.0 mEq/L), VO2max (28.3±6.2 vs. 30.6±7.1 ml/kg/min, p > 0.001; 29.3±5.4 vs. 29.6±5.2 ml/kg/min), factor k (−0.298±0.242 vs. −0.208±0.260, p < 0.05; −0.269±0.336 vs. −0.272±0.335), LVEF (58±11 vs. 67±10 %, p < 0.001; 55±11 vs. 54±12 %) and decreased LVDD (49.0±0.5 vs. 46.6±0.6 mm, p < 0.01; 47.7±0.5 vs. 47.4±0.5 mm), LVSD (36.1±0.5 vs. 31.6±0.4 mm, p < 0.001; 35.8±0.4 vs. 36.0±0.4 mm.
The present study supports the intake of oral Mg citrate and its favorable effects on exercise tolerance and left ventricular function during rest and exercise.