Submassive pulmonary embolism (December 2016)

TO THE EDITOR: I read with interest the review on submassive pulmonary embolism by Ataya et al¹ in the December 2016 issue. I had 3 questions or observations for the authors

First, systemic thrombolytic therapy for massive or hemodynamically unstable pulmonary embolism is given a grade 2C recommendation, similar to the level for select patients with submassive pulmonary embolism with low bleeding risk but at high risk of developing hypotension. The reference for this is the 2012 American College of Chest Physicians guidelines.² I would like to point out that these guidelines were updated and published in February 2016,³ and systemic thrombolytic therapy for massive pulmonary embolism now carries a grade 2B recommendation. Thrombolytic therapy still has a grade 2C recommendation for select patients with submassive pulmonary embolism.

Second, the Moderate Pulmonary Embolism Treated With Thrombolysis (MOPETT) trial is described as a randomized trial in patients with moderate pulmonary hypertension and right ventricular dysfunction. I would like to point out that right ventricular dysfunction was not a criterion for enrollment in the trial.⁴

Finally, catheter-directed thrombolytic therapy is mentioned as an option for select patients with submassive and massive pulmonary embolism. The advantage is believed to be due to local action of the drug with fewer systemic effects. Since the protocol involves alteplase for 12 or 24 hours with a maximum dose of 24 mg, and since in most cases pulmonary embolism originates in the lower extremity, are we not exposing these patients to further clot propagation for 12 or 24 hours without the benefit of concomitant systemic anticoagulation or an inferior vena cava filter?

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