Tissue plasminogen activator overdose in acute ischemic stroke patients linked to poorer functional outcomes.

Background: The dose of intravenous tissue plasminogen activator (tPA) administered in acute ischemic stroke patients is calculated using the patient's weight (0.9 mg/kg). Patients are rarely weighed before treatment in actual practice, although overestimating patient weights leads to higher doses of tPA, which may adversely influence outcome.

Methods: We investigated the weight used to calculate the dose of tPA compared to the actual measured weight in consecutive acute ischemic stroke patients treated over a 4-year period at our center. The rate of intracranial hemorrhage (ICH), discharge modified Rankin Scale (mRS) score, and mortality at 3 months were compared between groups, according to accuracy of the dose of tPA.

Results: We found that 140 of 164 (85%) acute ischemic stroke patients treated with tPA had a measured weight documented in the chart after treatment. Of these, 13 patients received ≥1.0 mg/kg and 16 patients received ≤0.8 mg/kg, based on a comparison of the weight used for the tPA dose calculation and the subsequent measured weight. Four of 13 (31%) patients treated with ≥1.0 mg/kg of tPA developed ICH. Patients who inadvertently received higher doses of tPA had a lower likelihood of a good functional outcome at discharge (mRS score 0-2; 0% v 34%; P = .009). No difference in 3-month mortality was observed, although patients who were not weighed in hospital had a threefold increase in discharge mortality (21% v 7%; P = .019).

Conclusions: Our findings provide support for the practice of accurately weighing all acute ischemic stroke patients before thrombolysis.