Attenuation over 24 hours of the efficacy of thrombolysis of pulmonary embolism among patients with cancer.

The efficacy and safety of thrombolysis in patients with cancer with pulmonary embolism is uncertain. Therefore we studied the effects of thrombolysis in 57 patients with cancer and 254 patients without cancer who were treated in five clinical trials with tissue plasminogen activator or urokinase for pulmonary embolism. Immediately after thrombolysis, the proportion of patients with and without cancer who improved on follow-up angiography (77% vs 73%; p = 0.65) was similar. The angiogrophic reduction in clot burden (1.83 +/- 0.27 vs 1.38 +/- 0.13; p = 0.13) was somewhat greater in patients with cancer than in patients without cancer. Twenty-four hours after initiation of thrombolytic therapy, the proportion of patients who improved on follow-up perfusion scan continued to be similar (72% vs 78%; p = 0.40). However, the extent of reperfusion at 24 hours was less in patients with cancer than in patients without cancer (6% vs 13% reperfusion of lung tissue; p = 0.007). These data suggest that patients with cancer should receive effective anticoagulation in the upper portion of the therapeutic range immediately after thrombolysis. It is possible that such a strategy might preserve initial improvement from thrombolysis and prevent attenuation of benefit during the ensuing 24 hours.