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Arterial Thrombembolism in Cats | VETgirl Veterinary CE Podcasts

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In today’s VETgirl podcast, we review feline arterial thromboembolism (FATE) – otherwise known as arterial thromboembolism (ATE). FATE is commonly associated with underlying cardiomyopathy and most commonly affects peripheral limbs. The high morbidity and mortality thus carry a generally poor prognosis, with euthanasia a frequent outcome. Cats may present with concurrent congestive heart failure (CHF). For the minority of cats who achieve partial or complete resolution of ATE, the likelihood of recurrent ATE is high.

So, Borgeat et al wanted to evaluate in this  a study called Arterial Thrombembolism in 250 cats in General Practice: 2004-2012 out of Royal Veterinary College. In this retrospective study, they evaluated cases of FATE presenting to two large 24 hour, multi-site general practices and one after-hours emergency service with predominantly non-specialized veterinarians. Overall, the prevalence of FATE was 0.26% (of their feline patients) with no seasonality reported; of these, 57.4% of cats were males. Of these cats, 29 cats (11.6%) had previously been diagnosed with cardiomyopathy; 17 cats (6.8%) previously diagnosed with hyperthyroidism. The remaining cats had never been previously diagnosed with cardiac disease.

Of these cases, 20.8% (50) episodes affected a single limb, while 77.6% (194) had two limbs affected. 68.2% of cats had an auscultated cardiac abnormality on presentation (e.g., murmur, arrhythmia, etc.). A large number of cats did not have sufficient data to determine the presence/absence of concurrent CHF (e.g., chest radiographs, etc.), but of those that did, 66.7% had concurrent CHF.

Overall, 61.2% (n= 153) of cats were euthanized at presentation. In 38% (n= 97) of cats, treatment was attempted. 68/250 (27.2%) survived beyond 24 hours (thus 68/97, or 70.1% of cats in which treatment was attempted). Similar to what what was reported in previous studies, the presence of a lower rectal temperature – among with presentation to Clinic #2 (e.g., referral) were independent predictors of 24 hour mortality. If Clinic #2 was removed from the analysis, no factors were predictive of 24 hour mortality.

Unfortunately, 55.9% of cats surviving > 24 hours were deceased within 7 days, predominantly due to euthanasia. Only 30 cats (12%) survived beyond 7 days in total. Predictors of 7 day mortality included lower rectal temperature and lack of treatment with aspirin, clopidogrel, or both. In those that survived, 14/30 (46.7%) had recurrence of ATE, with a median time to recurrence 118 days. Only 6 of these cats survived to > 1 year, with the majority being euthanized due to signs of recurrent ATE or CHF.

So, what do we take from this VETgirl podcast?

Although the majority of cats in this study were euthanized, particularly within the first 24 hours, 70% of cats did survive beyond 24 hour, which is noteworthy. Evaluating factors predictive of survival as it pertains to specific ATE treatment modalities (e.g., heparin, clopidogrel, aspirin, or some combination) was difficult in this study precisely due to the high percentage of euthanasia and low percentage of cats treated for the disease process. Hypothermia at presentation impacted 7 day survival. Evaluation of long-term survival factors and systemic complications of ATE was difficult due to small number or surviving cats and incomplete medical records. The authors do report that the number of cats with auscultated cardiac abnormalities on presentation is greater than previously reported.

Given the inherent limitations of retrospective data and the large number of cases euthanized on presentation, this study provides its greatest value in its evaluation of the characteristics of the ATE population at the time of presentation, which were summarized earlier. A relatively small number of cats with ATE will present with a prior documented history of heart disease or hyperthyroidism thus not providing most clinicians/owners with any forewarning. The first auscultation abnormality appears to come on presentation with ATE. Given the recent data on cardiac biomarkers, it seems reasonable that more of these cats will have detection of occult heart disease prior to ATE if veterinarians were to add BNP +/- troponin I levels to routine screening bloodwork panels in middle to older aged cats (Check out our podcast on cTnI levels for more information). Of the cats that were not euthanized at presentation, most survived beyond 24 hours but were euthanized prior to 7 days, likely reflecting lack of clinical improvement and owner financial considerations. Although no real conclusions can be drawn about treatment efficacy from this study due to small numbers of survivors, it is interesting that reduced survival was reported in the cats not receiving aspirin or clopidogrel (or both), which certainly warrants further investigation, ideally in a prospective manner and in comparison with heparin products.

The Bottom Line? ATE in cats presents with significant morbidity and low rate of previously detected occult cardiomyopathy. The rate of euthanasia within the first 24 hours is high and long-term survivors are few. The high rate of euthanasia due to patient morbidity and previously reported survival data made true evaluation of factors (treatment or other) that influence survival difficult in the present study. Larger studies of treated patients are necessary to determine whether antithrombotics such as aspirin, clopidogrel, or heparin can have significant impact on patient outcome. VETgirl’s advice in the meantime? Get those saddle thrombus cats on oxygen, adequate analgesic therapy, and some antithrombotic like aspirin and clopidogrel!

References:
1. Borgeat K, Wright J, Garrod O, et al. Arterial Thrombembolism in 250 cats in General Practice: 2004-2012. J Vet Intern Med 2014;28:102-108.

Abbreviations:
ATE: Arterial thromboembolism
CHF: Congestive heart failure

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