Half-dose thrombolysis for intermediate-high risk pulmonary embolism: Case series from a London hospital

Introduction: Early mortality from intermediate-high risk pulmonary embolism (PE) remains high. Full-dose thrombolysis reduces mortality at 7 days, but increases major bleeding, and does not reduce pulmonary hypertension incidence. An alternative approach may be ‘half-dose’ thrombolysis, which is not known to increase bleeding risk vs. anticoagulation alone. Our hospital protocol includes consideration of half-dose thrombolysis (alteplase 50mg) for intermediate-high risk PE. We describe a case-series of patients presenting with intermediate-high risk PE, aiming to assess the safety, outcomes and patient selection for half-dose thrombolysis. Methods: Records of medical admissions were reviewed retrospectively to identify cases of PE (1/3/15-28/2/17). Intermediate-high risk PE was defined according to ESC guidance. Results: 120 patients had confirmed PEs; 36 were intermediate-high risk. Of these, 22 received half-dose thrombolysis. Of those thrombolysed, median age was 40 years. All 22 were normotensive, had an sPESI score >1, and evidence of right heart strain on CT and/or echocardiogram (median troponin 80ng//L; median D-dimer 7.61mg/L). All 22 thrombolysed patients survived with no significant bleeding (median length of stay 5 days). No patients had evidence of CTEPH at follow-up. Among the 14 patients with intermediate-high risk PE who were not thrombolysed, reasons documented included age, clinical stability, and bleeding risks. Conclusions: Half-dose thrombolysis has appeared safe in our case-series, though careful patient selection is required. Further evaluation of half-dose thrombolysis to reduce early haemodynamic collapse in intermediate-high risk PE may be warranted.