From the Journals

Microthrombi, necrosis seen in COVID-19 hearts on autopsy


Anticoagulation, yes, but dose unclear

These findings clearly support the use of anticoagulation in hospitalized COVID patients, said Jeffrey Weitz, MD, director of the Thrombosis & Atherosclerosis Research Institute, McMaster University, Hamilton, Ont. But the details of how much anticoagulation, what kind, and for whom are still a moving target.

“I think what we can say at this point is that these autopsy findings fit with previous studies that have shown microthrombi in the lungs and thrombi in the legs and gut, and support the notion that these patients should receive prophylactic doses of anticoagulants if they’re sick enough to be hospitalized,” said Dr. Weitz.

“But it’s not as simple as to say that this study shows clots form in the heart of COVID patients and therefore more anticoagulation is going to be better than less anticoagulation,” he said in an interview.

Recent top-line findings from three linked clinical trials – REMAP-CAP, ACTIV-4, and ATTACC – show that full-dose anticoagulation was beneficial in moderately ill patients hospitalized for COVID-19 and reduced the need for mechanical ventilation.

Moderately ill patients are those not in intensive care and who did not require organ support, such as mechanical ventilation, at the time of enrollment.

However, the same group reported findings in December that showed that routine use of full-dose anticoagulation when started in the ICU in critically ill patients was not beneficial and possibly harmful.

Dr. Weitz was only a little bit surprised by this finding of potential harm in the sickest patients. “I figured everybody should get prophylaxis but I wasn’t sure that everybody should get intensified anticoagulant. But my assumption was that if anybody is going to benefit from it, it would be the ICU patients.”

It was notable, said Dr. Weitz, that levels of D-dimer, a fibrin degradation product, were not associated with outcomes. “So, it doesn’t seem to be that patients with evidence of more clotting are more likely to benefit, which might indicate that it’s not the anticoagulant effect of the heparin that’s helping, but maybe the anti-inflammatory effect. At this point, we just don’t know.”

All three studies have paused enrollment of the critically ill subgroup, but are continuing to enroll patients with moderate illness and expect to publish results in the coming months, according to previous coverage from this news organization.

The study was funded by CVPath, a nonprofit institute that receives funding from a number of different industry entities. Dr. Finn and Dr. Weitz reported no relevant conflicts of interest.

A version of this article first appeared on


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