Assessment of arrhythmias in healthy cats using 24-hour Holter monitoring: a cross-sectional study

BACKGROUND: The objective of this study is to investigate heart rate variables and evaluate the prevalence and characteristics of ventricular premature complexes (VPCs) and supraventricular premature complexes (SPCs) in healthy cats, using 24-hour Holter monitoring in the home environment. ANIMALS, MATERIALS AND METHODS: Thirty-five healthy, client-owned cats were enrolled and divided into two groups: Group 1 included cats aged < 7 years, and Group 2 included cats aged 7 years and older. Clinical examination, blood pressure measurement, total thyroxine levels, echocardiographic assessment and 24-hour Holter monitoring were performed for each cat. RESULTS: The average minimum (HRmin), mean (HRmean), and maximum heart rate (HRmax) were 103 ± 16.1 bpm, 151 ± 20.2 bpm, and 244 ± 22.6 bpm, respectively. Only HRmin differed between age groups (P = 0.027). Although the percentage of cats with VPCs was similar across groups (75% in Group 1 vs. 91% in Group 2, P = 0.391), older individuals had significantly more VPCs (median 13 vs. 3, P = 0.020), and a higher prevalence of complex arrhythmias (55% vs. 12%, P = 0.014). Older age (P = 0.009), male sex (P = 0.026) and lower body weight (P = 0.049) were significant predictors of the occurrence of VPCs, as well as daytime vs. nighttime (P = 0.013). The number of SPCs was similar in both groups (median and range- 0.5 [0–13] vs. 1 [0–31], P = 0.299). STUDY LIMITATIONS: A small sample size, unevenly distributed between age groups; uneven distribution of cat breeds; analysis of Holter data was made by a single operator; first period of the recording was not excluded from the analysis. CONCLUSIONS: Ventricular arrhythmias are common in healthy cats, and their prevalence and complexity increase with age. Age, sex and weight are significant predictors of the occurrence of VPCs, and VPCs tend to appear more during the day.