“There may be an evolution of the HERDOO2 decision rule to a lower age cut point. But that’s something that requires further study in postmenopausal women,” according to Dr. Rodger.
The investigators defined a first unprovoked VTE as one occurring in the absence during the previous 90 days of major surgery, a fracture or cast, more than 3 days of immobilization, or malignancy within the last 5 years.
Venous thromboembolism is the second most common cardiovascular disorder and the third most common cause of cardiovascular death. Unprovoked VTEs account for half of all VTEs. Their management has been a controversial subject. Both the American College of Chest Physicians and the European Society of Cardiology recommend continuing anticoagulation indefinitely in patients who aren’t at high bleeding risk.
“But this is a relatively weak 2B recommendation because of the tightly balanced competing risks of recurrent thrombosis off anticoagulation and major bleeding on anticoagulation,” Dr. Rodger said. He added that he considers REVERSE II to be practice changing, and predicted that once the results are published the guidelines will be revised.
Discussant Giancarlo Agnelli, MD, was a tough critic who gave fair warning.
“I am friends with many of the authors of this paper, and in this country we are usually gentle with enemies and nasty with friends,” declared Dr. Agnelli, professor of internal medicine and director of internal and cardiovascular medicine and the stroke unit at the University of Perugia, Italy.
He didn’t find the REVERSE II study or the HERDOO2 rule persuasive. On the plus side, he said, the HERDOO2 rule has now been validated, unlike the proposed DASH and Vienna rules. And it was tested in a diverse multinational patient population. But the fact that the HERDOO2 rule is only applicable in women is a major limitation. And REVERSE II was not a randomized trial, Dr. Agnelli noted.
Moreover, 1 year of follow-up seems insufficient, he continued. He cited a French multicenter trial in which patients with a first unprovoked VTE received 6 months of anticoagulants and were then randomized to another 18 months of anticoagulation or placebo. During that 18 months, the group on anticoagulants had a significantly lower rate of the composite endpoint comprised of recurrent VTE or major bleeding, but once that period was over they experienced catchup. By the time the study ended at 42 months, the two study arms didn’t differ significantly in the composite endpoint (JAMA. 2015 Jul 7;314[1]:31-40).
More broadly, Dr. Agnelli also questioned the need for an anticoagulation discontinuation rule in the contemporary era of new oral anticoagulants (NOACs). He was lead investigator in the AMPLIFY study, a major randomized trial of fixed-dose apixaban (Eliquis) versus conventional therapy with subcutaneous enoxaparin (Lovenox) bridging to warfarin in 5,395 patients with acute VTE. The NOAC was associated with a 69% reduction in the relative risk of bleeding and was noninferior to standard therapy in the risk of recurrent VTE (N Engl J Med. 2013 Aug 29;369[9]:799-808).
“Why should we think about withholding anticoagulation in some patients when we now have such a safe approach?” he asked.
Dr. Rodger reported receiving research grants from the French government as well as from Biomerieux, which funded the REVERSE II study. Dr. Agnelli reported having no financial conflicts.