How much protection does clopidogrel provide to cats with hypertrophic cardiomyopathy?

Cats with hypertrophic cardiomyopathy (HCM) have a risk of developing aortic thromboembolism (ATE). Clopidogrel reduces the risk of redeveloping ATE and delays recurrence of ATE in cats that have experienced an ATE episode. Consequently, cardiologists have recommended administering clopidogrel to cats as a primary preventative, suggesting that all cats with severe HCM be administered clopidogrel. However, clopidogrel is unpalatable in its manufactured format, making such administration problematic for many clients. Therefore, estimating the potential benefit of administration might help clinicians determine on a case-by-case basis the need to treat cats with clopidogrel. Relatively simple statistical analyses of currently available data, along with certain assumptions and extrapolations, allow such an estimation of benefit in terms of relative and absolute risk reduction conferred by clopidogrel. Using this approach, and provided certain assumptions are true, clopidogrel likely confers a reduction in risk of ATE in cats with moderate to severe HCM of approximately 3% to 4%. Given the difficulty of administering clopidogrel to cats, clinicians should weigh these relatively small potential benefits against the potential harms (difficulty of administration) and not necessarily insist that clients administer clopidogrel.