Intravenous magnesium therapy in acute myocardial infarction (MI) has
been shown to be beneficial in many studies. However, these effects ar
e not consistent from one trial to another, and their clinical signifi
cance is often questionable. A total of 78 consecutive patients were i
ncluded in a prospective placebo controlled, randomized study of the e
ffects of intravenous magnesium sulfate infusion in acute MI. Of these
, 52 (66%) received intravenous streptokinase and the rest belonged to
a non-thrombolysed group. These patients were randomized to receive m
agnesium sulfate infusion (8 mmol over 5 min followed by 65 mmol over
24 h) or placebo. The end points were serious arrhythmias, left ventri
cular ejection fraction (LVEF) and death during hospital stay and at t
he end of 28 days. LVEF measured by radionuclide ventriculography at d
ischarge (9 +/- 5 days) was similar in two groups(41 +/- 11 vs. 39 +/-
10; magnesium vs, placebo respectively, P = 0.40). However, the LVEF
of the placebo-treated thrombolysed group was higher than the non-thro
mbolysed group (42 +/- 10 vs. 37 +/- 0, P = 0.02). Incidence of nonsus
tained ventricular tachycardia (NSVT) was higher with placebo than wit
h magnesium (50% vs. 23% respectively, P < 0.02, odds ratio = 0.29; 95
% confidence intervals (CI) 0.1-0.85). Mortality during hospital stay
and at the end of 28 days was also similar in both the groups. Thus, t
he administration of magnesium infusion as an adjunct to thrombolytic
therapy remains to be of questionable benefit.