It’s finally here: Pulmonary Embolism

One of my loves (shout out to those who know me with my PERT scrub cap on, courtesy of Dr. Horowitz). PE is one of my favorite medical derangements to manage (I think there are generally these two schools anyways: those who love and those who don’t care). It’s so medically complex and there are multiple ways of managing it and not very straightforward; this leaves room for thinking. There are emerging markers you can check if you suspect it and radiologic images usually make it very obvious…usually. Few types: Massive vs sub-massive vs low risk. Massive PE entails hemodynamic compromise/cardiogenic shock, clot-in-transit (scary). Sub-massive means stable but can include RV strain on TTE or chest CTA and elevated biomarkers. Low risk is PE without any of the above. I think lingo is a bit confusing too. I think massive is high risk, submassive is intermediate risk then you have just low risk.

When you run into a pt with PE, you need to first determine if it’s massive or submassive (it’ll be pretty clear if you just look at the patient, then the vitals). Then call your PERT (pulmonary embolism response team). The PERT is a multi-disciplinary approach that gets activated and gathers all your major PE players on the phone — your cardiology team, critical care doc, cardiac surgeon, IR, pharmacist, etc. From there, the patient can be presented and a plan can be streamlined without the need for multiple consults and hours of back-and-forth. Thanks to Mass General for creating the first PERT team in 2012!

There are some rough guidelines out there regarding PE management but because of the complexities, severities, “low” registry data, and new innovations, there is not always a clear answer (which is why PERT can talk about it). ACC and ESC guidelines are fairly similar in categorizing and stratifying risk. The risk calculator is called the pulmonary embolism severity index or PESI and they’re divided into classes. The classes tell you what your 30-day mortality risk is. And your PESI score in turn might dictate your management. There are 11 clinical criteria: age>80, sex (Male is +10), cancer (+30), heart failure (+10), chronic lung disease (+10), tachycardia HR>110 (+20), hypotension SBP<110 (+30), tachypnea ≥30 (+20), hypothermic < 36C (+20), AMS (+60), and hypoxia SpO2<0.90 (+20). We don’t have to memorize this because we have something called MDCalc. Table is as follows (% being risk of 30-day mortality):

• 0–65 = Class 1= 0–1.6%
• 66–85 = Class 2 = 1.7–3.5%
• 86–105 = Class 3 = 3.2–7.1%
• 106–125 = Class 4 = 4–11.4%
• >125 = Class 5 = 10–24.5%

There’s the sPESI (simplified PESI), which is easier to remember but I’m not going to write it down.

According to the ACC (updated 2020), patients are considered:

• Submassive/intermediate risk if they have a PE with PESI Class 3–5, RV strain, +trop, or elevated BNP
• Massive/high risk if they have a PE with hypotension, clot in transit, syncope, or cardiac arrest
• Low risk if they have a PE without symptoms, HDS or e/o RV strain

I think a step-wise approach might be the easiest to digest since the recommendations are so broad and there are numerous management strategies for PEs.

1. Diagnose (or suspect) the PE
2. Massive vs submassive vs low risk? Using clinical criteria, biomarkers, and imaging
3. If you have a crashing patient: cardiac arrest/hypotensive, they may need mechanical support so do this first (VA ECMO, resuscitate) with bridge to systemic tPA, CDT or surgical embolectomy.
4. Massive/high risk? Start AC (UFH vs fondaparinux vs LMWH) with consideration of systemic tPA, CDT/lytics or surgery. If relative CI to systemic, use catheter-directed-lytics. If absolute CI to systemic, use catheter- directed- thrombectomy. Same thing goes for submassive/intermediate.
5. Submassive/intermediate? Start AC and if HDS start DOAC. Consider CDT if there are relative or absolute CI to systemic tPA
6. You have a massive or submassive PE with absolute CI to systemic tPA, in shock that also have clot in transit (especially across PFO) or RV thrombus? Consider surgical embolectomy

Absolute CI to systemic tPA:

• active bleeding, prior ICH, structural brain disease, recent brain/spine surgery, recent head trauma/ brain injury

Relative CI to systemic tPA

• SBP>180, DBP>100, recent bleeding, recent surgery or invasive procedure, ischemic CVA within 3 mo, traumatic CPR, pericarditis, diabetic retinopathy, pregnancy, >75 yo, low body weight

Some CDT out there are EKOS, Inari Flowtriever, Indigo Penumbra, and Thrombolex.

The European Society of Cardiology (ESC) have very similar risk stratification but breakdown the intermediate into low and high intermediate. But basically:

High early mortality risk = hemodynamic compromise with PE

Intermediate high early mortality risk = PE with RV strain + elevated trop

Intermediate low early mortality risk = PE with either RV strain OR elevated trop

Low early mortality risk = none of the above

• If HDUS or RV strain for high or intermediate risk is noted, PESI calculation is not necessary.

My favorite part: Now what?

That was a whole ton of information. What will I do differently? A lot! I didn’t know more than half of this information. I always activate my PERT. But now I can recognize the risk factors and perhaps fight for certain patients I think are good candidates for therapy. I usually always start heparin drip anyways while I come up with a plan. If I have a patient with no CI to tPA who is on a bit of pressor since they’re hypotensive with e/o RV strain (I see this a lot whether it’s directly on TTE or there is a >1 RV:LV ratio with contrast reflux in the IVC), I’ll probably reach for tPA or ask my IR and MICU attendings to see if they want to enroll this patient in a CDT trial. But if they look fine w/o radiologic evidence of badness, we can start the DOAC and maybe discharge home the next day. I think it’s clear when patients are HDUS and need surgery or mechanical support.

I’m going to post this first. I’ll add more in a bit. I have an anecdotal case report I’d like to talk about. Enjoy.

Dk