a) What is meant by the term intermediate risk pulmonary embolism (PE) (submassive PE)?
b) Discuss the role of thrombolysis in patients presenting with intermediate risk PE. (70% marks)
Latest definition according to European Society of Cardiology guideline [European Heart Journal (2020) 41, 543_603]
Intermediate Risk Pulmonary embolism can be either:
:PE without haemodynamic instability in a patient with evidence of RV dysfunction (dilatation on ECHO/CT, ECG changes, BNP) and myocardial necrosis (troponin)
PE without haemodynamic instability in a patient who has one or more of the following features- age>80, cancer, Chronic heart failure, PR>110, SBP<100, SaO2< 90%. In addition, they may have either RV dysfunction or elevated cardiac troponin or none of these.
Intermediate Risk Pulmonary embolism is when PE presents without haemodynamic instability (SBP<90mmHg) but with evidence of RV dysfunction (dilatation on ECHO/CT, ECG changes, BNP) or myocardial necrosis (troponin).
Rationale for using thrombolysis (reperfusion treatment) is that it leads to faster improvement in pulmonary obstruction. However, the treatment decision needs to be balanced with the risk of life- threatening bleeding.
The first part of this question is easy. The terms are actually interchangeable (Rali & Criner, 2018); "submassive" appears to be an AHA classification, whereas "intermediate risk" is from the ACCP, but basically both involve the same features:
The ESC also split the category into "intermediate to low risk" for those who only have one of RV dysfunction and biomarkers, whereas the "intermediate to high risk" group has both. The college mention the 2019 ESC guidelines, in case anybody needs that reference as a link.
Now, the role of thrombolysis is a more delicate question.
First of all, from an initial reading of the question text did the college mean "systemic" or "catheter directed", or both? One would have to assume both.
Rationale for thrombolysis in this group:
Full dose systemic thrombolysis for submassive PE:
Low dose systemic thrombolysis for submassive PE
Catheter-directed thrombolysis for submassive PE
Konstantinides, Stavros V., et al. "2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS) The Task Force for the diagnosis and management of acute pulmonary embolism of the European Society of Cardiology (ESC)." European Heart Journal 41.4 (2020): 543-603.
Krishnan, Abhinav C., et al. "Effectiveness of Catheter Directed Thrombolysis for Massive and Submassive Pulmonary Embolism Compared to Systemic Thrombolysis or No Thrombolysis." Circulation 140.Suppl_1 (2019): A17230-A17230.
Bhamani, Amyn, Joanna Pepke-Zaba, and Karen Sheares. "Lifting the fog in intermediate-risk (submassive) PE: full dose, low dose, or no thrombolysis?." F1000Research 8 (2019).
Levis, Joel T. "ECG diagnosis: Pulmonary embolism." The Permanente Journal 15.4 (2011): 75.
Rali, Parth M., and Gerard J. Criner. "Submassive pulmonary embolism." American Journal of Respiratory and Critical Care Medicine 198.5 (2018): 588-598.
Wang, Chen, et al. "Efficacy and safety of low dose recombinant tissue-type plasminogen activator for the treatment of acute pulmonary thromboembolism: a randomized, multicenter, controlled trial." Chest 137.2 (2010): 254-262.
D'Auria, Stephen, et al. "EXPRESS: Outcomes of Catheter-Directed Thrombolysis versus Standard Medical Therapy in a Retrospective Propensity Matched Cohort of Patients with Acute Submassive Pulmonary Embolism." Pulmonary Circulation (2019): 2045894019898368.
Pei, Dorothy T., et al. "Meta-analysis of Catheter Directed Ultrasound Assisted Thrombolysis in Pulmonary Embolism." The American journal of cardiology (2019).