Thrombolysis for acute submassive pulmonary embolism: CON viewpoint

The normotensive patient with confirmed pulmonary embolism (PE) and right ventricular (RV) dilatation presents a significant dilemma to clinicians. On one hand, a string of publications have demonstrated that RV dysfunction is associated with adverse outcomes in patients with PE;1–5 on the other, thrombolysis carries a significant risk of bleeding.6 ,7 However, evidence emerging in recent years has provided a strong case against using thrombolysis in this setting, greatly aiding clinical decision-making in submassive PE (taken here to mean confirmed PE in a normotensive patient with evidence of RV dilatation and/or RV dysfunction and/or pulmonary hypertension). The aim of this article is to review some of the most important data surrounding this debate. The decision to administer systemic thrombolysis would be easier if submassive PE had a high mortality rate that was significantly reduced by treatment. However, this is not the case. In larger studies, inhospital or 30-day mortality for submassive PE treated without thrombolysis is typically between 1% and 5%,3 ,8–11 though lower and higher rates have been described.12–14 In the excellent, landmark randomised controlled trial (RCT) of thrombolysis versus heparin alone for submassive PE, mortality was 3.4% in the thrombolysed group and 2.2% in the ‘heparin-alone’ group.8 The argument is commonly made that trials exclude elderly patients or patients with comorbidities, artificially reducing mortality rates. However, the large RIETE registry also suggests a 90-day mortality of around 3% in patients with submassive PE.15 The problem for advocates of thrombolysis in PE is that it may be technically impossible to demonstrate beneficial effects on mortality. This is because an RCT comparing thrombolysis and standard treatment would require prohibitively large numbers of patients to generate sufficient statistical power to detect a clinically meaningful difference in mortality. Faced with this problem, those who …