BACKGROUND:Thrombolytic therapy is widely accepted for massive pulmonary embolism (PE) due to the high mortality risk associated with standard anticoagulation alone. Its role in submassive PE, however, has remained controversial. We aimed to evaluate whether the selective use of systemic thrombolytic therapy with intravenous tissue plasminogen activator (IV-tPA) improves the survival of patients with submassive PE at increased risk for clinical deterioration. METHODS:A total of 184 consecutive patients diagnosed with acute PE by chest thoracic angiography (CTA) were included in a retrospective study. Pulmonary artery obstruction and right/left ventricular dysfunction were evaluated by CTA and echocardiography. Medical history and simplified PE Severity Index (sPESI) were assessed at diagnosis. Hemodynamic and respiratory status were recorded at diagnosis, admission to pulmonary unit and prior to thrombolytic therapy. Patient survival was assessed at 30 of 90 days from diagnosis by CTA. RESULTS:All low risk patients (36%) per sPESI survived. Among the 117 remaining patients, 31% received IV-tPA. Respiratory failure was associated with decreased age-adjusted survival (P = 0.005). Among patients with respiratory failure selected for IV-tPA, age-adjusted survival was improved significantly compared to others (P = 0.043). CONCLUSIONS:Thrombolytic therapy for hemodynamically stable PE patients with respiratory failure may improve survival. TRIAL REGISTRATION:MMC-0216-14.