Transient Myocardial Thickening in Cats Associated with Heart Failure

J Vet Intern Med. 2018 Jan;32(1):48-56. doi: 10.1111/jvim.14897. Epub 2017 Dec 15.

Abstract

Background: Cats with hypertrophic cardiomyopathy (HCM) and congestive heart failure (CHF) can have resolution of both left ventricular hypertrophy and CHF.

Objectives: To describe the clinical characteristics of cats with transient myocardial thickening (TMT) and CHF compared with a control population of cats without resolution of HCM.

Animals: A total of 21 cats with TMT, 21 cats with HCM.

Methods: Retrospective study. Clinical records at 4 veterinary centers were searched for TMT cases and a control group of cats with HCM and CHF. TMT was defined as initial maximal left ventricular wall thickness (LVWT) ≥6 mm with left-sided CHF, with subsequent resolution of CHF, reduction in left atrium/aorta (LA/Ao), and LVWT<5.5 mm. HCM was defined as persistent LVWT ≥6 mm.

Results: Cats with TMT were younger (2 [0.4-11.4] years) than cats with HCM (8 [1.6-14] years) (P < 0.0001), and antecedent events were more common (15/21 versus 6/21, respectively) (P = 0.01). In cats with TMT, LVWT normalized from 6.8 [6.0-9.7] mm to 4.8 [2.8-5.3] mm and LA/Ao decreased from 1.8 [1.6-2.3] to 1.45 [1.2-1.7] after a mean interval of 3.3 (95% CI: 1.8-4.7) months. CHF recurred in 1 of 21 TMT and 15 of 21 cats with HCM. Cardiac treatment was discontinued in 20 of 21 cats with TMT and 0 of 21 HCM cats. All cats with TMT survived, whereas 8 of 19 cats with HCM died during the study period.

Conclusions and clinical importance: TMT occurs in younger cats, and antecedent events are common. The prognosis is better in cats with CHF associated with TMT than HCM.

Keywords: HCM phenocopy; Hypertrophic cardiomyopathy; Myocarditis; Takotsubo cardiomyopathy.

MeSH terms

  • Age Factors
  • Animals
  • Cardiomyopathy, Hypertrophic / drug therapy
  • Cardiomyopathy, Hypertrophic / pathology
  • Cardiomyopathy, Hypertrophic / veterinary*
  • Cat Diseases / pathology*
  • Cats
  • Echocardiography / veterinary
  • Female
  • Heart Failure / pathology
  • Heart Failure / veterinary*
  • Hypertrophy, Left Ventricular / drug therapy
  • Hypertrophy, Left Ventricular / pathology
  • Hypertrophy, Left Ventricular / veterinary*
  • Male
  • Retrospective Studies