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

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.

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.

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).

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