Throughout this year, we’ve covered various aspects of the anticoagulation puzzle. One post walked through the drug options available for ECMO patients and the tradeoffs between them. Another broke down the alphabet soup of labs used to monitor those drugs and why they so often disagree with each other. We even got into some of the more niche, less familiar monitoring tools out there, like TEG (thromboelastography).

A new trial published in July 2026 throws a wrench into how the field has historically approached anticoagulation on ECMO. The trial, called RATE (Reduced Anticoagulation Targets in Extracorporeal life support), asked a bold question: could ECMO patients get by on lower anticoagulation targets, or even switch to subQ anticoagulants similar to the drugs already given to most inpatients for VTE prophylaxis?

For years, most programs have leaned toward the higher end of the dosing range just in case, treating a heavier hand as the safer default. That instinct made sense with older circuits, which were rougher on blood and more prone to clotting on contact. As we noted in our anticoagulation options piece, modern circuits with more biocompatible coatings and steadier flow have chipped away at that risk, which is part of why some programs have already started feeling comfortable with low (to no) anticoagulation targets.

RATE is one of the first trials large enough to actually test whether that instinct holds up with real outcomes data behind it, rather than just circuit design and clinical hunch.

What the Study Looked At

RATE enrolled 330 adults on ECMO across seven ICUs in the Netherlands and randomized them into three groups.

• One group got the approach most programs already use, IV unfractionated heparin (UFH) given as a continuous IV drip, titrated to a higher aPTT target.
• The second group also received IV heparin, but titrated to a lower target.
• The third group used low molecular weight heparin (LMWH) instead, given as a subcutaneous injection rather than a continuous infusion, dosed by weight and kidney function.

LMWH isn’t one specific drug, it’s a category, and it includes medications most hospital teams already know well, like enoxaparin (Lovenox). The difference is that most inpatients who get a dose of it are getting a flat, low prophylactic dose meant to keep blood from clotting while someone is lying in a hospital bed, not to actively manage clotting risk on a circuit. RATE used LMWH at a therapeutic dose instead, adjusted for weight and kidney function rather than the standard one-size-fits-all prophylactic dose, so it’s a real step up from the version most inpatients receive.

Patients with mechanical mitral valves, a known blood clot, or a history of heparin-induced thrombocytopenia (HIT) were excluded, since those patients need a different anticoagulation conversation entirely. Everyone else was followed for bleeding, clotting, and survival at six months.

What They Found

Perhaps surprisingly, backing off the anticoagulation target may have reduced harm without increasing thrombotic risk.

Among patients receiving standard-dose IV heparin, 81% experienced at least one of three major outcomes: severe bleeding, severe clotting, or death within six months. That fell to 72% with lower-dose IV heparin, and 75% with subQ LMWH. Major bleeding was less common with both lower-dose IV heparin and subQ LMWH, and importantly, neither approach led to an obvious increase in serious clotting events.

An important note, though: the study wasn’t designed to prove that lower-dose IV heparin or subQ LMWH was better. It was designed to show that they weren’t meaningfully worse than standard-dose IV heparin, and both passed that test.

Every anticoagulant involves a tradeoff between how well it prevents clotting and how quickly a team can back off if a patient starts bleeding or needs an urgent procedure. The biggest advantage with IV heparin is that it’s a continuous drip, which means it can be turned down or off in minutes and reversed almost immediately with protamine. However, LMWH doesn’t have that same quick off switch. Once it’s given as a shot, it takes longer to wear off, and there isn’t a reliable reversal drug for it the way there is for IV heparin.

That distinction can be a big deal for ECMO patients, who often and unexpectedly require procedures, line changes, or trips to the OR. In RATE, patients on LMWH ended up switching to a different strategy more often than either IV heparin group, mostly for exactly this reason: an upcoming procedure made LMWH’s slower, harder to reverse profile a poor fit in the moment. This is an important detail to keep in mind if choosing LMWH.

Study Details and Caveats

RATE was an open label trial, meaning the bedside team knew which strategy each patient was on. That’s a real limitation, since knowing the assignment could shape decisions like how quickly to transfuse or how aggressively to chase a slightly abnormal lab.

As mentioned earlier too, it was also a non inferiority trial, which means researchers weren’t trying to prove the lower doses worked better. They set out to prove the lower doses weren’t worse by more than a small margin they defined ahead of time. By that measure, both lower intensity strategies cleared the bar, but that’s a different bar than “this is the new superior approach.”

It’s also worth remembering where and how this trial was run. RATE took place at high volume centers in the Netherlands using modern circuits, so it doesn’t tell us much yet about how this holds up at smaller programs, in pediatric ECMO, or in the patients who were excluded from the trial altogether. And since RATE titrated dosing using aPTT, the same test we’ve flagged before as one that can be thrown off by inflammation, liver dysfunction, and other factors that have nothing to do with anticoagulant effect, it’s fair to wonder whether these results would look the same if the trial had titrated a different way.

Future Practice Considerations

RATE doesn’t settle the question of how much anticoagulation ECMO patients need, but it does is give programs that are already questioning their aPTT targets something new to bring into that conversation.

Lower dose IV heparin is probably the more approachable of the two strategies to start discussing, if only because it uses the same drug and the same monitoring rhythm most teams already know, just aimed at a different number. SubQ LMWH is more of a case by case fit, and the procedural tradeoffs covered earlier are worth weighing carefully before it factors into a protocol conversation at all.

None of that makes RATE any less worth watching. It’s a large, well designed trial asking a question a lot of programs have already been debating on their own, and it adds real data to that conversation rather than closing it. Sorting out where the field lands next will take more studies and more real-world experience across different programs and patient populations.

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The RATE trial will likely be a hot topic at this year’s ELSO Conference. We rounded up this trial along with a few other sessions worth watching for in our latest newsletter. Sign up here to get it in your inbox.