By Jeffrey Zimmet, MD, PhD
Associate Professor of Medicine, University of California, San Francisco; Director, Cardiac Catheterization Laboratory, San Francisco VA Medical Center
SOURCE: Hassell ME, et al. Antiplatelet therapy following transcatheter aortic valve implantation. Heart 2015. pii: heartjnl-2014-307053. doi: 10.1136/heartjnl-2014-307053. [Epub ahead of print].
Currently, guidelines in both Europe and the United States advise that patients post-transcatheter aortic valve replacement (TAVR) undergo between 3 and 6 months of dual antiplatelet therapy (DAPT) treatment, which typically includes a low-dosage of aspirin and a thienopyridine, like clopidogrel. At present, antiplatelet and antithrombotic medication usage following TAVR procedures is founded less on hard data than on experiential empiricism, and is partially taken from experiences involving coronary stenting. While dual antiplatelet therapy is linked with higher rates of bleeding when compared with aspirin treatment, there is meager evidence supporting its efficacy post-TAVR.
Hassell et al compiled data from two registry studies and two randomized control trials (RCTs), pooling information regarding 672 TAVR patients treated with either aspirin alone (n=415) or DAPT (n=257). Patients treated with warfarin and those treated with clopidogrel, alone, however, were excluded from the study. After accounting for propensity matching, the final analysis encompassed 434 patients: 235 from the matched cohorts and 199 from the RCTs.
In the 30-day comparison of the DAPT and the aspirin monotherapy groups, net adverse ischemic and thrombotic events — including stroke — displayed no observable differences. Likewise regarding individual endpoints, no significant difference was observed between all-cause mortality. There was, however, a trend of less dangerous or major bleeding with the aspirin treatment alone. Clinical outcomes for the included studies were evaluated further separately. In both the RCTs and the matched cohorts, acute coronary events and all-cause mortality were not increased in the aspirin treatment group.
The authors conclude that the merit of coupling a thienopyridine such as clopidogrel with aspirin in treating post-TAVR patients is under scrutiny as it potentially increases patients’ hazard of bleeding without offering equitable benefit.