Alternatives to systemic thrombolysis in submassive saddle pulmonary embolism

In the recent case report, the allusion to the use of thrombolytic therapy for saddle pulmonary embolism (saddle PE)1 raises important questions regarding the relative merits of various treatment strategies for management of submassive saddle PE,2,3 given the haemorrhagic risk associated with systemic thrombolytic therapy.4 Firstly, in an analysis of six randomized controlled trials which enrolled patients with submassive PE, and in whom systemic thrombolysis was compared with anti-coagulation alone, thrombolysis was associated with increased risk of major bleeding [Odds Ratio (OR); 3.56, 95% Confidence Interval (CI): 2.12–5.97] and intracranial bleeding (OR: 6.79, 95% CI: 1.51–30.50).4 The reported case1 best fits the category of submassive (i.e. intermediate risk) PE, given the fact that he had right ventricular dysfunction, albeit with a systolic blood pressure of >90 mmHg. Stigmata of massive PE were absent, namely, 15 min or more duration of systolic blood pressure < 90 mmHg (not due to a cause other than PE), pulselessness, or heart rate of < 40 beats/minute with signs or symptoms of shock.5 On its own, saddle PE does not necessarily confer an adverse prognosis.6 It is only when it is associated with haemodynamic compromise that an adverse outcome can be expected.7 Angiojet rheolytic thrombectomy addresses the management of saddle PE in the submassive category, albeit through the medium of a retrospective review.2 In that review, 13 PE patients (8 with submassive PE, 5 with massive PE) were managed by rheolytic thrombectomy, to the total exclusion of thrombolytic therapy. The sole anti-thrombotic modality was peri-procedural heparin infusion. The aim of rheolytic thrombectomy was to decrease clot burden through clot extraction (even though this might be incomplete) so as to allow improvement of oxygenation and haemodynamic status. Overall, a significant (P < 0.005) improvement in both parameters was achieved without incurring the penalty of haemorrhagic complications requiring blood transfusion.2 Fixed low-dose ultrasound assisted catheter-directed thrombolysis is the ‘halfway house’ strategy both for massive PE and submassive PE.3 In the latter retrospective study, comprising 52 patients (14 with high risk PE, 38 with intermediated risk PE) low-dose recombinant tissue plasminogen activator was administered by catheter concurrently with intravascular ultrasound. A significant (P < 0.01) improvement in mean systemic blood pressure, mean pulmonary artery blood pressure and mixed venous oxygen saturation was documented in the 38 patients with intermediate risk PE, at the penalty of only one major bleeding complication.3 What we now need is a prospective study comparing strategies2,3 and with anti-coagulation alone in submassive PE. Conflict of interest: None declared.