Protective effect of intravenous magnesium in acute myocardial infarction following thrombolytic therapy

The role of intravenous magnesium therapy in patients with acute myocardial infarction (AMI) who received thrombolytic therapy is controversial. The r esults from previous clinical trials were not in consonance. We therefore c onducted a prospective, randomized, double-blind, placebo controlled study in 350 patients with confirmed AMI during the period January 1994 to Decemb er 1996. The role of intravenous magnesium sulphate therapy (2 g over 5 min followed by 16 g over 24 h) was evaluated in patients with AMI who receive d thrombolytic therapy. Study group consisted of 169 patients who were admi nistered magnesium sulphate. Control group comprised of 181 patients who we re given isotonic saline. Among those in the magnesium group, 70% received magnesium within 6 h after the onset of symptoms. All patients received mag nesium immediately after the completion of thrombolytic therapy. Patients w ere followed up for 30 days after AMI. The number of deaths in the study group was 6 (3.5%) compared with control arm in which 18 patients (9.9%) died (P value <0.01 95% Confidence interval s [CI] 1.2 to 11.6). Ventricular arrhythmias were also less in the magnesiu m arm; 27 patients [13%]) compared with 83 patients (48.6%) in the control arm (P value 0.00001 95% Cl 26.7 to 44.5). In the magnesium group 15 patien ts (8.8%) had re-infarction compared with 23 patients (12.7%) in the placeb o arm (P value not significant). Post myocardial infarction angina was obse rved in 47 patients (27.8%) in the magnesium arm compared with 60 patients (33.1%) in the placebo arm (P value not significant). The main side effect of intravenous magnesium was transient hushing observed in 152 (90%) patien ts. Intravenous magnesium sulphate in patients with AMI is a safe and usefu l adjunct to thrombolytic therapy in reducing the shea-term mortality and v entricular arrhythmias after AMI. (C) 1999 Elsevier Science Ireland Ltd. Al l rights reserved.