Episode 69- Do anticoagulated patients with ACS get IV heparin?

Hello and welcome to Episode 69 of ER-Rx. This week, we’re answering a very important clinical question in the setting of acute coronary syndromes (ACS). That question is; do we give heparin to patients who are already anticoagulated with warfarin or a DOAC (apixaban or rivaroxaban) at home? This is a great question, and luckily there is one European document from 2018 that goes over what to do for these patients. As we go forward, I’ll specifically talk about unfractionated IV heparin (UFH), since that’s what my site uses, but I am aware that other sites may use enoxaparin or bivalirudin for ACS- and if you do- you’ll have to do your own digging for dosing recommendations. Also remember that we don’t have the best evidence for any of these recommendations, and most of them are based on observational studies and expert opinion.

So, let’s start with the emergent scenario that the ER staff will most often see; a patient with a STEMI or Non-ST elevation-ACS (NSTE-ACS) undergoing emergent primary PCI. If the patient is on warfarin or a DOAC at home, you would just give the standard heparin bolus dose (60 units/kg IV) regardless of when the patient last took their home anticoagulant. Easy- so that answers about 90% of the questions that I get- so if you take anything away from this episode, let that be it. But there are some other, slightly more complex scenarios that we can quickly discuss.

If you have a patient with NSTE-ACS where invasive treatment is delayed, the recommendations for heparin are a little different. If the patient is on a DOAC, they again recommend giving IV heparin at standard doses (60 units/kg IV) irrespective of the time the patient last took their DOAC. It’s important to note that some sites may do things a little differently here- like hold the heparin bolus and just start the heparin infusion, or give a lower heparin bolus dose along with the infusion. But, if the patients are on warfarin with an INR > 2.5, we have the option of holding the heparin bolus or giving a lower dose (30-50 units/kg IV). If the INR is In the setting of elective PCI we again have some minor differences. If the patient is on warfarin, we can consider holding the heparin bolus or giving a lower dose (30-50 units/kg IV), especially if the INR is > 2.5. The data for patients on DOACs is much more limited and inconsistent. But overall, the recommendation is to usually hold DOACs for 12-48 hours, depending on the agent the patient is on, their renal function, and the cardiologist’s or institution’s preferences. They also recommend not bridging these patients while the DOAC is held. This is really the only time we would consider interruption of the patient’s oral anticoagulation in the setting of ACS- in every other scenario we would continue the warfarin or the DOAC peri- PCI. You would then give the standard heparin bolus at the time of PCI.

So now that we have the anticoagulation aspect figured out, what about the aspirin and P2Y12 inhibitor? This is more straightforward. All patients with ACS, regardless of if they’re on warfarin or a DOAC will get the aspirin load immediately. All patients should also receive a P2Y12 inhibitor, with 300-600 mg (300 mg dose for patients on warfarin, 300-600 mg for patients on DOAC given limited data) of clopidogrel (Plavix) being preferred over ticagrelor (Brilinta) and prasugrel (Effient) due to higher bleeding rates with these other agents. And please note that GP IIb/ IIIa inhibitors should be avoided if at all possible, unless or course it’s ordered by cardiology for bail-out, life-threatening situations.

I don’t have time to go into post-procedural and post-discharge therapy- both of which can get pretty complex, but please read the guideline for yourselves to get a better handle on this aspect of care. I will post some diagrams that summarize most of the things I discussed today on errxpodcast.com and the @errxpodcast Instagram page. So make sure you check those out.

In conclusion, for almost all situations you would see in the hospital, do not hold oral anticoagulation prior to PCI, unless the patient is on a DOAC and PCI is delayed- in which case you can consider holding the DOAC until the procedure. Crystal clear. This recommendation comes from a few studies that showed that holding oral anticoagulation and bridging with heparin or enoxaparin leads to higher bleeding rates. Next up, in any anticoagulated patient with ACS going straight to the cath lab, give a standard heparin bolus regardless of when the patient took their dose of the oral anticoagulant. For NSTE-ACS where invasive treatment is delayed, it gets a little nuanced. Here, we can hold the heparin, give a full bolus dose, or give a lower bolus dose depending on the patient’s INR if they are on warfarin, or we can go ahead and give the standard heparin bolus if they are on a DOAC. Remember that all of this should be discussed with your cardiology team because each institution has their own preferences.

As always, thank you so much for your time. Don’t forget to click on the show-notes, where you can find links to where you can leave me a review, subscribe to the pod, check out my references, and even support the show on BuyMeACoffee.com. With that said, I’d like to shout out friend-of-the-pod ‘MNPHARMD’ for hitting me up with 5 coffees- thank you so much!