The guidelines allow for the addition of short-term clopidogrel to an oral anticoagulant (OAC) in patients with an established OAC indication, such as atrial fibrillation (AF), who undergo transcatheter aortic valve replacement (TAVR). But does the extra antithrombotic protection come with safety issues?
It apparently did in the POPULAR-TAVI trial, which saw an excess of major and minor bleeding in such patients already on an OAC when they underwent TAVR and who then took the antiplatelet agent for the next 3 months.
The patients who instead continued on their OAC as the only post-TAVR antithrombotic, compared with those on double therapy, showed a 37% lower 1-year risk of any bleeding, including major and disabling bleeding.
Importantly, they didn’t seem to pay a price in excess ischemic events, such as stroke or myocardial infarction (MI).
The trial argues against adding clopidogrel on top of OAC in TAVR patients with an OAC indication in order to reduce their risk of bleeding, Jurriën ten Berg, MD, PhD, St. Antonius Hospital, Nieuwegein, the Netherlands, told theheart.org | Medscape Cardiology.
Whether the ischemic event risk was comparable with and without clopidogrel is less clear. “As the study is not powered for the ischemic end points, the answer is less definite. But we did not see a hint of a higher ischemic event rate, especially stroke, in the OAC-alone group,” ten Berg said.
“So we are pretty confident in saying that OAC alone is the optimal treatment.”
The results of POPULAR-TAVI were presented by Vincent Nijenhuis, MD, also from St. Antonius Hospital, on March 29 during the virtual presentation of the American College of Cardiology 2020 Scientific Session/World Congress of Cardiology. Nijenhuis is also first author on the trial’s simultaneous publication in the New England Journal of Medicine.
The only reason to add an antiplatelet in TAVR patients who need to be on an OAC for another indication is to prevent ischemic events like MI, stroke, or death, agreed George D. Dangas, MD, PhD, Mount Sinai Hospital, New York City, for theheart.org | Medscape Cardiology.
But that protection apparently wasn’t needed; for patients on OAC only, “the overall risk–benefit ratio was favorable for them both ways. Although the study is small, I think the findings would be clinically meaningful,” said Dangas, who was not involved in POPULAR-TAVI but was lead author on the GALILEO trial publication.
GALILEO tested a direct oral anticoagulant (DOAC) against dual antiplatelet therapy in patients undergoing TAVR but without a conventional OAC indication. The trial was halted because the DOAC group started to show an excess of bleeding, thromboembolic events, and mortality.
Most POPULAR-TAVI patients were on vitamin K antagonists, but about a quarter were taking DOACs. Clopidogrel was given on an open-label basis.
The trial suggests that, for TAVR patients with an indication for lifelong OAC, “it does appear to be safe to give only an anticoagulant, whether it’s warfarin or a DOAC, and not add clopidogrel,” Robert O. Bonow, MD, Northwestern University, Chicago, told theheart.org | Medscape Cardiology.
“The bottom line appears to be that it’s no worse, and is probably better in terms of bleeding events,” said Bonow, who wasn’t involved in POPULAR-TAVI.
But there are difficulties in interpreting the trial that stem from its design and other issues, he said. For example, it can’t really be concluded that adding an antiplatelet agent to OAC in such patients who undergo TAVR, according to commonly practiced techniques, will increase the risk of bleeding compared with OAC alone.
To begin with, Bonow said, substituting aspirin for clopidogrel might have produced better double-therapy results. But the bigger issues, Bonow said, center on the discretion its operators had in whether to maintain or suspend the patients’ OAC during the TAVR procedure, as well as the unusual bleeding definitions used in the trial.
The first POPULAR-TAVI primary end point was any bleeding that met Valve Academic Research Consortium (VARC) criteria; the second was nonprocedural bleeding that met the Bleeding Academic Research Consortium (BARC) definition.
“Because the VARC-2 classification does not distinguish between procedure-related and nonprocedure-related bleeding events, procedure-related events were defined as BARC type 4 severe bleeding,” the trial’s journal report states. Therefore, “most bleeding at the puncture site was counted as nonprocedure-related.”
It may be Bonow’s biggest issue with the trial, he said. “They’re terming these events that occurred periprocedurally, in the first day or first hours of the procedure, as being ‘nonprocedural’ because they didn’t represent severe BARC bleeding, where you have a subarachnoid hemorrhage or require transfusions.”
An editorial accompanying the trial report also knocks this aspect of the trial design. Although the trial “confirmed” a higher incidence of any bleeding in the double-therapy group, “there are concerns regarding the classification of bleeding and the reliability of secondary outcome analysis,” writes Frederick Feit, MD, NYU Grossman School of Medicine, New York City.
“Bleeding occurring during TAVI or the index hospitalization was unadvisedly defined as non-procedure related, even if it occurred at the access site,” the editorial notes.
Ten Berg noted that procedural bleeding is frequent in TAVI, but the VARC-2 definition doesn’t accommodate them. So “we also used the BARC definition for procedural bleeding, BARC-4,” he told theheart.org | Medscape Cardiology.
“However, BARC-4 describes bleeding during surgery, and it turned out that in POPULAR- TAVI only one patient had BARC-4 bleeding. So we do not at all agree with the editorial.”
Still, the trial’s reported event-rate curves show that “most of the step-up in bleeding, in either arm of the trial, occurred immediately,” Bonow observed. A more consistent, flat trend followed thereafter out to 3 months.
“So half of the bleeding in both arms of the trial occurred at the site of the arterial puncture. Though it wasn’t considered severe, it was indeed periprocedural,” Bonow said, interpreting the results.
The POPULAR-TAVI journal report says the procedures were performed according to local site protocols, and site physicians were allowed to decide whether to continue or suspend OAC. But “the trial protocol advised physicians to continue oral anticoagulation during admission for the TAVI procedure.”
Many of the patients, regardless of randomization group, “went through the procedure under full anticoagulation,” Dangas agreed. POPULAR-TAVI, it seems, “is the first anticoagulation study ever to start anticoagulation before the procedure.”
Bleeding event rates in the trial “are somewhat high because of this unusual procedural feature of the study,” Dangas said.
“It’s therefore not surprising that so much of the bleeding occurred in the first hours of the procedure itself,” observed Bonow.
The trial enrolled 313 patients in four European countries who were on OAC for an approved indication, predominantly AF, and underwent TAVR. Their mean age was about 81 years, and 45.4% were women. They were randomly assigned to receive or not receive clopidogrel in a loading dose, followed by 75 mg/d on top of their OAC for 3 months, and were followed out to a year.
All bleeding that met VARC-2 criteria, the first primary end point, occurred in 21.7% of the 157 patients on OAC alone and 34.6% of the 156 who received double therapy (risk ratio [RR], 0.63; 95% CI, 0.43 - 0.90; P = .011).
The second primary end point, “nonprocedural” bleeding that met BARC-4 criteria, occurred in 21.7% and 34.0%, respectively, of patients (RR, 0.64; 95% CI, 0.44 - 0.92; P = .015).
There were also two secondary composite outcomes. The first consisted of nonprocedural bleeding, cardiovascular (CV) death, any stroke, and MI, and was seen in 31.2% of patients on OAC alone and 45.5% of those on OAC plus clopidogrel (RR, 0.69; 95% CI, 0.51 - 0.92), an absolute difference that was within the prospectively defined noninferiority margins.