Fibrinolysis for Intermediate-Risk Pulmonary Embolism

To the Editor: In the Pulmonary Embolism Thrombolysis (PEITHO) study (April 10 issue), 1 a bolus of unfractionated heparin was withheld from 303 patients because they had just received subcutaneous low-molecular-weight heparin or fondaparinux. Low-molecular-weight heparin in particular has a slow onset of action, taking 4 to 6 hours to reach full effect. 2 This delay in the effect of treatment may have been unfavorable to patients not receiving tenecteplase, among whom the incidence of hemodynamic decompensation (often within the first day after randomization) was higher than that among patients receiving tenecteplase. Guidelines support the safety of low-molecular-weight heparin in patients with . . .