NEW YORK, August 7 (Praxis Press) Thrombolytic therapy for acute myocardial infarction is equally effective when delivered as a bolus injection and as a 60 to 90-minute infusion; however, the relative safety of these two delivery methods is unknown. Using meta-analysis, Mehta and colleagues studied the risk of intracranial hemorrhage in patients receiving thrombolytic therapy as a bolus or as an infusion. The analysis included seven randomized trials with a total of 103,972 patients. The risk of intracranial hemorrhage was higher in patients receiving boluses relative to patients receiving infusions (odds ratio, 1.25; p = 0.003); this difference was most marked when the same drug was administered by bolus or infusion (odds ratio, 1.75; p = 0.0001). However, differences also existed when newer-generation bolus drugs (reteplase, lanoteplase, and tenecteplase) were compared with standard infusion drugs (alteplase and streptokinase) (odds ratio, 1.25, p = 0.02). In contrast, rates of nonhemorrhagic stroke, 30-day mortality, and reinfarction were similar for both delivery methods. Bolus thrombolytic therapy is more convenient, but is associated with an increased risk of intracranial hemorrhage.