Blunt Cerebrovascular Trauma: Anticoagulation or Antiplatelet Therapy?

Thanks to Li for sending out a nice summary of this subject with excerpts from the relevant UpToDate article. The bottom line is that they acknowledge the lack of prospective data on this problem, but do recommend anticoagulation for grade IV vascular injuries (complete occlusion).

The authors reference a trauma guideline that makes the same recommendation, and it turns out that the three authors of the UpToDate article are also authors, including the lead author, of the guideline. This increases our confidence that these UpToDate articles are written by knowledgeable people, but it does make it even more important to look into the source documents since the UpToDate authors are mainly referencing their own work. Following are some quotes and commentary from the guideline (emphasis added and citations removed):

Because there are no published prospective randomized clinical trials that have generated class I data, the recommendations herein are based on published observational studies and expert opinion of Western Trauma Association members . . .

. . . A few retrospective, uncontrolled case series, as well as more recent large reports from Memphis and Denver suggest that systemic heparinization and antiplatelet therapy (clopidogrel 75 mg daily or aspirin 325 mg daily) are equally efficacious in stroke prevention . . .

. . . In the absence of controlled data, systemic heparin may be preferred among patients with neurologic symptoms and in those who have no contraindications. The Memphis data demonstrate systemic heparinization’s clear efficacy in improving neurologic outcomes among symptomatic patients . .

The Memphis paper was an observational study of 87 blunt carotid (not vertebral) injuries in 67 subjects.  47 subjects received heparin, 8 had no treatment, 6 received aspirin, and 1 underwent surgical treatment. For the 47 subjects treated with heparin, outcomes were “good” in 26; “moderate” in 7; and “bad” in 14. For the 15 who did not receive heparin, outcomes were “good” in 3; “moderate” in 1; and “bad” in 11. Heparin was associated with better outcomes as compared to no heparin; p < 0.01. Because only 6 of the 15 “no heparin” subjects received aspirin, I interpret this study to show that heparin is better than no heparin, but not necessarily better than aspirin. That comparison wasn’t done (the word “aspirin” appears just once in the entire article!)

. . . Furthermore, although statistical significance was not achieved, the large series in Denver suggests that heparin may be superior to antiplatelet therapy in stroke prevention (p = 0.07) and in neurologic improvement after ischemic insult (p= 0.15).

The Denver paper was also an observational study, authored by the same group who wrote the UpToDate article and the guideline, further demonstrating the degree of self-reference with respect to this question. There were 3 strokes among 33 subjects treated with aspirin (9%) and one among the 84 treated with heparin (1%) p = 0.07. There was no statistically significant difference in neurologic outcomes in heparin-treated versus no heparin subjects (p = 0.15), which again isn’t the comparison we’re interested in anyway. They wrote that they were designing a randomized trial to answer this question, but it appears to have never taken place.

And, of course, there were significant bleeding events reported in both of the above studies.

So, it appears that the evidence for heparin being superior to aspirin for stroke prevention in the setting of blunt cerebrovascular trauma boils down to one observational study whose authors then wrote a guideline largely on the strength of their own article, followed by an UpToDate entry that references their guideline. I’m not in the trauma world, so don’t know how much weight the Western Trauma Association carries. For what it’s worth, that organization is not listed in the National Guideline Clearinghouse database.

Does any of this prove that aspirin is in fact equivalent or better than heparin in this situation? Certainly not. I just want to make the point that we don’t really know and so, as is often the case in medicine, must make individual decisions based on our best judgment.

About Justin A. Sattin

I'm a vascular neurologist and residency program director. I created this blog in order to share some thoughts with my resident and other colleagues, and to foster my own learning as well.
This entry was posted in Medical Knowledge and tagged , . Bookmark the permalink.

2 Responses to Blunt Cerebrovascular Trauma: Anticoagulation or Antiplatelet Therapy?

  1. Georgios Manousakis says:

    This is about a separate topic in antithrombotics for stroke prevention. I am sorry I am using the reply function, as it is not possible for me to open a new topic in the website.
    Internet resources and colleagues at work recently made me aware of the CHANCE study, a study using short-term dual antithrombotics (aspirin+clopidogrel) for secondary prevention of recurrent ischemic stroke in a Japan population. The regimen was quite complex, but the results appeared to show a meaningful absolute and relative risk reduction for recurrent ischemic stroke in the short term (90 days), without a concurrent increase in the rate of hemorrhagic complications.
    A similar (although not exactly the same in terms of design) study, the POINT study, is currently conducted in the US.
    During my 3 years of residency in Wisconsin, we had multiple discussions in morning reports, rounds, journal clubs, conferences, etc. about the MATCH, and other studies of dual antiplatelet (aspirin+clopidogrel) long term use for stroke prevention, plus the SPS-3 study got published after I completed my residency. The results of those studies were sufficient to convince me that long-term combination of drugs does not appear to be superior to aspirin or clopidogrel monotherapy in terms of secondary prevention, and is associated with higher risks of bleeding.
    My question is: If the POINT study reproduces the results of CHANCE, should we revisit our therapeutic approach/standards of care on short-term antiplatelet therapy after ischemic stroke?

    Thanks

    • Justin A. Sattin says:

      Hi George!

      UW is actually a site for POINT, and yes, if POINT replicates these findings, then I think we’ll (or at least I) will change my practice. A short duration of dual antiplatelet therapy would then be indicated for many patients.

      The problem is to ensure that patients are taken off the dual therapy at the appropriate time. Too often these drugs are started and then remain forever . . .

Comments are closed.