Selections from current literature: magnesium, myocardial infarction and meta-analysis

If the results of LIMIT-2, the two meta-analyses reviewed and the cumulative meta-analysis by Lau et al. are viewed in aggregate, there can be very little doubt regarding the beneficial effects of i.v. magnesium on mortality in suspected acute MI. The results of ISIS-4 should strengthen these odds ratios and help clarify the role of magnesium and arrhythmias in acute MI. Furthermore, the combined effect of i.v. magnesium and thrombolytics will again be focused upon. Though the cardioprotective effects of magnesium are unknown, this should only spur more studies to elucidate these mechanisms and should not be a reason to delay the inclusion of i.v. magnesium in the usual regimen for treating suspected acute MI. The regimen of i.v. magnesium needs to be standardized. Further studies are also needed to evaluate whether oral magnesium can be used as tertiary prevention for MI. Finally, meta-analyses are studies of studies that are valid and reliable if they follow certain rules. This is true of all types of research. Due to the exponential increase in the medical literature of these types of studies, and the fact that they may eventually supplant the traditional narrative review, it is incumbent upon physicians to understand the process by which a meta-analysis is conducted.