VTE Prophylaxis or Anticoagulation in COVID: Visiting the Guidelines

If you continue reading on this page, you’ll note that I have attempted to tackle the whole conundrum of anticoagulation in COVID patient with the pendulum swinging. My first post on the matter was back on 4/6/20 (when this post was initially created) and the second was on 4/12/20. My attempts to keep modifying my practice based on experience and the guidelines were quite frustrating. At first, I provided full anticoagulation to every COVID patient. As the waves ran through my area, I noted complications from this. Especially as our ICU patients would have prolonged lengths of stay. This only magnified the risk of the bleeding complications.

Today is 2/13/2022. Two years into this mess. I do not recall seeing robust anticoagulation in COVID guidelines from the American Thoracic Society nor the Society of Critical Care Medicine. Although I may have forgotten about them or missed them. CHEST shared their guidelines last night and will be what we will be going with moving forward. The main question here is whether to use DVT prophylaxis or full anticoagulation in different subgroups of COVID patients. Risk of bleeding need to be considered, obviously.

Hospitalized and Acutely Ill: Preventing VTE in the Ward

Therapeutic anticoagulation. Heparin gtt or full dose lovenox/enoxaparin.

Should “Intermediate Dose” anticoagulation be used in the ward?

No. We should not use intermediate dose anticoagulation in COVID patients. Either provide them with VTE prophylaxis dosing, or pull the trigger with full anticoagulation.

Hospitalized and Critically Ill: Preventing VTE in the ICU

Prophylactic dosing should be used here, not full anticoagulation in our COVID patients. The data here is the most clear cut. From my personal experience, I have seen too many bleeding complications. This is simply because these unfortunate patients sit in our ICUs for weeks on end.

Should “Intermediate Dose” anticoagulation be used in the ICU?

The answer here is, once again, no.

Wrapping up the guidelines on Anticoagulation and COVID

Note that there’s no decision-making based on d-dimer. The authors stated that an increased d-dimer may be at increased risk of thrombosis. They also stated that “elevated D-dimer levels that were associated with increased morbidity and mortality”. Given this finding, should we stop checking d-dimer levels on our patients? It is my opinion that we should once the decision is made to start the patient on full anticoagulation upon admission.

The question then becomes of what to do with the full-dose heparin/enoxaparin once the patient becomes sick enough to need the ICU. This becomes case-by-case, of course.

04/06/2020: Anticoagulation in COVID-19: Should we empirically start?

Should start anticoagulation in COVID patients? Simple question, not so simple answer. Autopsies have found occlusion and microthrombosis formation in the small vessels of the lungs. We all know that people have just decided to drop dead for one reason or another after looking fine. Could this also be happening in the heart and kidneys? Can we at least band-aid this by anticoagulating somewhere in the course?

What we’re seeing in practice.

At the time of this writing, 75% of the COVID ICU patients I’ve personally cared for have developed DVT’s of some sort during their hospital course and are currently on full anticoagulation. But could we have predicted this was going to occur and have been proactive when it comes to all this micro and macro thrombi we are seeing? By the way, I have reached out to some hematologists I know and trust for their opinions and no one really knows. Even though I started writing this post yesterday, Josh Farkas beat me to the punch today.

Let’s look at the data regarding anticoagulation and COVID

The paper I’m covering today was published on March 27th and came out of China. I’m late to the game. It is a retrospective study. They described “sepsis-induced coagulopathy” based on PT, platelets, and SOFA score.

They found that if the the SIC score was greater than or equal to 4 and the patients had received heparin, there was a decrease in their 28 day mortality from 64.2% to 40%. The number needed to treat with all its limitations was just 4.1 If the SIC score wasn’t elevated, it really didn’t make a difference. The D-dimer also held its own if it was greater than 6. When this is the case, patients who received heparin had a mortality of 32.8% versus 54.8% without it (NNT=5.1). This isn’t the best data in the world and has numerous limitations that you can look at yourself to help you better interpret the study, but I know I will personally be formulating some anticoagulation strategies for these patients in the absence of a large clinical trial. Potential benefit has to be greater than the risks, of course.

It is important to note that the dosing utilized in this paper is comparable to our DVT prophylaxis doing. My curiosity ultimately stems from the utility of full dose anticoagulation. Could that hypothetically lead to even fewer deaths? I don’t know.

Has anyone seen any data where patients who are chronically anticoagulated have less severe COVID? I’m curious. A question for someone smarter than me: Would there be a difference between using heparin, enoxaparin, or moving straight to the DOACs? I would like to limit the exposure of my nurses in titrating heparin drips.


I have written and said this before but I am quite convinced that many COVID patients need full anticoagulation. My opinion, not medical advice. This is due to what I have seen in my clinical practice, what others have anecdotally mentioned, and post-mortem data. We need more data to find out when to start it. Obtaining CT scans of the chest and having a radiology tech come in to scan everyone’s extremities may not be realistic. This article was published yesterday and I learned about it from Josh Farkas (@pulmcrit). I’ll read his take after I put this out. There’s ultimately no randomized control trial for anticoagulation in these patients and this is pure clinical gestalt. Please strongly weight risks vs. benefits if you go down this route.

In my practice, I have been keeping track of numerous parameters to try my best to decide when to pull the trigger of when to start anticoagulation. It’s a big mystery. As the authors of this paper mentioned, we don’t know what is the prevalence of venous thromboembolism in patients with severe COVID-19 infections. They looked at checking d-dimers to predict VTE in these patients.

Retrospective study published on 4/9. They looked at 81 ICU patients in Wuhan, China. They did lower extremity ultrasounds. I am personally reporting that I’ve seen upper extremity VTE’s so these could be enough to change the study. They also performed numerous other lab tests.

What they found:

25% of patients (n=20) had lower extremity VTE. Again, they didn’t check the uppers.
8 of these 20 patients died.
VTE group: older patients, lower lymphocyte counts, longer PTT (all statistically significant)

What lab value did they find to be most helpful to start anticoagulation in COVID?

D-dimer greater than 1.5mcg/mL.
85% Sensitivity. 88.5% Specificity. 94.7% Negative predictive value.

For some background, an elevated d-dimer is a sign of “excess coagulation activation and hyperfibrinolysis”. Once you start anticoagulation, the d-dimer should start coming down. I am seeing this in my practice. I haven’t decided where to pull the trigger, though. Anecdotal evidence. Poo poo evidence.


Click here for breakdowns of other COVID-19 Articles.


Moores LK, Tritschler T, Brosnahan S, Carrier M, Collen JF, Doerschug K, Holley AB, Iaccarino J, Jimenez D, LeGal G, Rali P, Wells P, Thromboprophylaxis in Patients with COVID-19. A Brief Update to the CHEST Guideline and Expert Panel Report, CHEST (2022), doi:https://doi.org/10.1016/j.chest.2022.02.006.
Link to Article

EJ Tang N, Bai H, Chen X, Gong J, Li D, Sun Z. Anticoagulant treatment is associated with decreased mortality in severe coronavirus disease 2019 patients with coagulopathy [published online ahead of print, 2020 Mar 27]. J Thromb Haemost. 2020;10.1111/jth.14817. doi:10.1111/jth.14817
Link to Abstract
Link to FREE PDF

Cui, S., Chen, S., Li, X., Liu, S. and Wang, F. (2020), Prevalence of venous thromboembolism in patients with severe novel coronavirus pneumonia. J Thromb Haemost. Accepted Author Manuscript. doi:10.1111/jth.14830
Link to Website with Article
Link to Article

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