Ambulatory electrocardiogram recordings in cats with primary asymptomatic hypertrophic cardiomyopathy

Objectives The aims of the study were to determine the heart rate, rhythm, number of ventricular premature complexes (VPCs) and atrial premature complexes (APCs) in unsedated cats with asymptomatic hypertrophic cardiomyopathy (HCM), using 24 h ambulatory electrocardiogram (ECG) (Holter) in the home environment and to compare the results with those from healthy control cats. Methods Fifteen privately owned cats with asymptomatic HCM entered the study. Data from 23 healthy cats, previously published by our group, were used as the control. Clinical examination, measurement of blood pressure, echocardiographic examination, Holter recordings and biochemical analyses were performed in all cats. Holter recordings were obtained in the home environment. Results Three-lead ECGs of good quality were obtained from 15 cats with HCM. The median heart rate was 145 (interquartile range [IQR] 137-184) beats per minute for the cats with HCM. All cats with HCM presented with normal sinus rhythm; 60% of cats had intermittent sinus arrhythmia. Median number of VPCs was 3 (IQR 1-17). Three cats had APCs and three cats had both escape beats and intermittent sinus arrhythmia. Conclusions and relevance Asymptomatic cats with HCM had few VPCs and APCs on 24 h ambulatory ECG in the home environment. Intermittent sinus arrhythmia was observed in 60% of cats with HCM. The present study shows that the heart rate and the number of VPCs and APCs in cats with asymptomatic HCM are similar to that found in healthy control cats.