Supraventricular Tachycardia vs Atrial Fibrillation in Cats

In the Literature

Greet V, Sargent J, Brannick M, Fuentes VL. Supraventricular tachycardia in 23 cats; comparison with 21 cats with atrial fibrillation (2004-2014). J Vet Cardiol. 2020;30:7-16.

The Research …

Supraventricular tachycardia (SVT) and atrial fibrillation (AF) are rhythm disturbances that have the potential to result in prolonged tachycardia and clinical signs. Determining the existence of underlying structural heart disease is important in determining treatment and prognosis. SVT and AF have been reported in humans and dogs in the absence of underlying heart disease.^1-3 Although less is known about AF and SVT in cats, one retrospective study of 50 cats with AF suggested that most also had structural heart disease.⁴ 

This retrospective study evaluated the medical records of 44 cats with SVT (23) or AF (21) to compare signalment, presenting complaints, cardiac phenotype, and survival time. Most (32) were male, and breeds included domestic shorthair, domestic longhair, Maine coon, British shorthair , Birman, Persian, ragdoll, Devon rex, and sphynx. No significant differences were noted in sex, age, or breed of cats with AF versus cats with SVT. All cats with AF had echocardiographic evidence  of left or right atrial enlargement, whereas 4 cats with SVT had no evidence of underlying cardiac disease. Left atrial diameter was significantly larger in cats with AF than in cats with SVT. Median survival time was 58 days (range, 1-780 days) in cats with AF and 259 days (range, 2-2,295) in cats with SVT.

… The Takeaways

Key pearls to put into practice:

• Similar to humans and dogs with SVT or AF, the prognosis for cats appears to be dictated by the presence or absence of underlying heart disease and, more specifically, atrial enlargement.

• AF without underlying heart disease is rare in cats; however, some cats with SVT may have structurally normal hearts.

• Assessing left atrial size and identifying the presence of underlying cardiac structural changes are important aspects in managing feline arrhythmias. Although thoracic radiographs and circulating biomarkers are generally useful for identifying moderate to severe heart disease, mild to moderate heart disease is often missed. Clinicians should therefore learn basic echocardiographic imaging techniques or have access to a mobile ultrasonographer that is skilled in obtaining these images, as this is critical for patient management and advising pet owners about prognosis.