The same observations pertain to the subset of patients alluded to by the ISIS-4 Investigators who were randomized within six hours of symptoms onset and had a high multivariate prognosis score. In the absence of details on the timing of administration of magnesium, with particular reference to the elapsed time from onset of thrombolytic therapy, even in high risk subgroups, the findings of the ISIS-4 study remain compatible with the hypothesis that early administration of magnesium (particularly before reperfusion occurs) is associated with a reduction in mortality from acute myocardial infarction.