Study Shows That A Nonantithrombotic Strategy May be Acceptable Following TAVR For Select Patients

Results from the OCEAN-TAVI registry indicate that a non-antithrombotic strategy may be reasonable following transcatheter aortic valve replacement (TAVR) in select patients.1

Transcatheter aortic valve replacement is now a well-established strategy for symptomatic severe aortic stenosis across the entire spectrum of surgical risk. As the typical population tends to be older with multiple morbidities, bleeding and thromboembolic events are key targets for improving long-term outcomes. Pertinent adverse endpoints include both thromboembolic — stroke, myocardial infarction, valve thrombosis, valve hemodynamic deterioration, atrial fibrillation related emboli – and bleeding events — mostly procedure-related, gastrointestinal, and neurovascular. Several studies have clarified appropriate strategies to mitigate these risks. The currently accepted approach includes single antiplatelet treatment (SAPT) for most, short-term dual antiplatelet treatment (DAPT) for those with recent coronary stenting, and sole oral anticoagulant (OAC) without adjunctive antiplatelet therapy for those with a separate indication for anticoagulation.2 This is a departure from previous recommendations calling for short term DAPT prior to lifelong SAPT in patients without an indication for OAC. However, even the newer more conservative paradigm leaves behind patients with severe symptomatic aortic stenosis being considered for TAVR who have excessive bleeding risk and are potentially intolerant of even aspirin monotherapy.

Insights from the OCEAN-TAVI registry begin to fill this gap. This is a nationwide observational, multicenter study across 15 Japanese hospitals. Investigators compared 3 antithrombotic strategies in patients undergoing TAVR between October 2013 and May 2020: 1) nonantithrombotic therapy (N = 293); 2) SAPT (N = 1,354); and 3) DAPT (N = 1,928). They excluded patients who received OAC or who had procedural complications. The primary outcome was the incidence of net adverse clinical events (NACEs) including both ischemic and bleeding endpoints: cardiovascular death, stroke, myocardial infarction, and life-threatening or major bleeding.

After a median follow-up of 841 days, they found no difference in NACEs between the three groups after adjusting for confounders using multivariable Cox regression modeling. The cumulative incidence for NACEs were 14% for None, 14.7% for SAPT, and 16.2% for DAPT. There was a lower incidence of bleeding events in patients taking no antithrombotics (None vs SAPT: aHR 0.63, P = 0.12; None vs DAPT: aHR 0.51, P = 0.04). There was no difference in valve performance according to mean pressure gradient and indexed effective orifice area between the groups. Hypoattenuated leaflet thickening (HALT) was noted in 8.5% of patients in the nonantithrombotic group, well within published rates. Reasons for electing for a nonantithrombotic strategy included low platelets, anemia, age, body weight, renal dysfunction, active malignancy, and prior bleeding; 85% of these patients were deemed to have a high bleeding risk by attending physicians.

These results are telling. A substantial portion of patients treated with TAVR in this cohort were not prescribed any antithrombotic agents (N = 293, 8.2%), mostly related to an estimation of high bleeding risk; this is not an uncommon scenario. Reassuringly, this nonantithrombotic approach was not associated with excess NACE events after adjusting for known confounders but was associated with lower bleeding events. Further, valve thrombosis and performance were no different from those receiving SAPT or DAPT. Importantly, this is a retrospective observational study with potential for unknown confounding and likely not adequately powered for all reported outcomes. With TAVR extending to lower risk patients with greater longevity, longer follow-up will be valuable. Overall, this is hypothesis generating but does provide some reassurance in real world practice about the acceptability of electing for a nonantithrombotic approach for those who are deemed to have a high bleeding risk.

While SAPT will continue to be the recommended approach following TAVR in patients without another indication for DAPT or OAC, these data should comfort the heart team when considering offering TAVR to patients who are unable to tolerate any antithrombotic therapy.