Evaluation of spontaneous variability in the frequency of ventricular arrhythmias in Boxers with arrhythmogenic right ventricular cardiomyopathy.
OBJECTIVE
To evaluate spontaneous variability in the frequency of ventricular arrhythmias and assess the influence of day of ECG recording and day of week on arrhythmia frequency in Boxers affected with arrhythmogenic right ventricular cardiomyopathy (ARVC).


METHODS
Prospective study.


METHODS
10 Boxers with ARVC with prior ambulatory ECG recordings that included > or = 500 ventricular premature complexes/24 h.


METHODS
Consecutive 24-hour ambulatory ECG recordings were obtained during a 7-day period in each dog. The number of ventricular premature complexes and grade of the arrhythmia were obtained from each recording. For each dog, the number of ventricular premature complexes for each recording was evaluated to identify any differences relative to the day of recording (recording 1 to 7) and day of the week (Monday through Sunday).


RESULTS
Spontaneous variability accounted for as much as 80% of the change in frequency of ventricular premature complexes in dogs with frequent arrhythmias; this value was almost 100% in dogs with less frequent arrhythmias. Grade of arrhythmia was less variable but was also inversely related to frequency of arrhythmia. No significant differences in frequency values were identified among days of recording or among days of the week.


CONCLUSIONS
Changes of < or = 80% in the frequency of ventricular arrhythmias may be within the limit of spontaneous variability in dogs with ARVC. This degree of variability should be considered in evaluations of ambulatory ECG recordings, particularly in the assessment of the efficacy of antiarrhythmic drugs.
Spier
Alan W
AW
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University Columbus, OH 43210, USA.
Meurs
Kathryn M
KM
D000818:Animals; D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000503:physiopathology / Q000662:veterinary*; D016022:Case-Control Studies; D004283:Dog Diseases / Q000503:physiopathology*; D004285:Dogs; D015716:Electrocardiography, Ambulatory / Q000662:veterinary; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D011446:Prospective Studies; D012016:Reference Values; D013045:Species Specificity