What's Hot in Clots Special Edition: Insights from ISTH 2026

Unless I’m fortunate to have readers from the Southern hemisphere, it’s getting really hot in many places around the world, and the clots are also hot with ISTH! I wasn’t able to make to Paris, but here’s my take on some of the key studies:

Aspirin or anticoagulation for hip/knee surgery: The saga continues!

A new randomized trial presented with simultaneous publication in NEJM showed that among over 5,000 participants undergoing hip or knee surgery, being assigned to low-dose aspirin (81 mg/d) versus rivaroxaban 10 mg once daily was associated with comparable incidences both for new symptomatic proximal DVT or PE and major or clinically relevant nonmajor bleeding. 

If you think you have the answer, I should warn you that these are far from CRISTAL clear. Moreover, the situation is quite PEPPERy—although full PEPPER results have not been published yet. There are two things that I’m certain about: not everyone does well on low-dose aspirin, and I’ve been too often on the receiving end of major VTE in people undergoing major orthopedic surgery (perhaps as many as pooled numbers in one large trial)! But there’s  a second point that I also agree with: not everyone needs anticoagulation. In fact, most people will likely not need it. The real question is which subgroup benefits most from anticoagulant prophylaxis.

This Hydra is not scary—and can be beneficial!

The YEARS algorithm has been widely validated and is being used overall, even in subgroups like pregnant individuals. Now in this noninferiority trial of patients with cancer, named Hydra, the authors show that many CTPAs can be safely averted thanks to the YEARS algorithm. As a child, I was scared after hearing the name Hydra. Guess what? This one is not scary at all—and may indeed be beneficial! Read more.

Improving outcomes for women with classical hematological diseases

What a timely commissioned article by an esteemed group of authors. This manuscript includes many pearls of wisdom for clinical care and for policy, including future considerations by the European Medicines Agency. A humble suggestion to Lancet and authors: Shouldn’t such an important article be open access? I was able to read thanks to institutional access, but would love to see this accessible for all, if possible. Read more.

Breakthrough recurrent VTE is an important risk marker in cancer…so what happened?

A provocative analysis from the API-CAT trial shows that recurrent events correlate with worse outcomes, including death in patients with cancer. That’s quite understandable to me. I still have a few questions in mind, though…

How often did these recurrences occur in the face of factors such as surgery or cytopenias that resulted in treatment interruption?  And what proportion of index events and outcome events were isolated subsegmental PE or isolated distal DVT? Those diagnoses are often more questionable and I generally think of them less critically as failure of anticoagulation. Read more.