Ambulatory Electrocardiographic Monitoring and Outcome in 338 Asymptomatic Doberman Pinschers (1999-2007)
ACVIM 2008
M.L. O'Sullivan; M.R. O'Grady; A.R. Pastor; C. Walker
Ontario Veterinary College, University of Guelph
Guelph, ON, Canada

The purpose of this study was to describe the frequency and character of ventricular arrhythmias on ambulatory ECG (Holter) monitors in a population of asymptomatic Doberman pinchers and to determine whether any of the indices related to ventricular premature contractions (VPCs) were predictive of the combined endpoint of sudden death (SD) or congestive heart failure (CHF).

Recordings from 388 Dobermans were previously collected between 1999 and 2007. Exclusion of those known to be in CHF at the time of the recording and those with recording duration less than 8 hours resulted in a total of 370 asymptomatic Dobermans. Holter analysis was previously performed using the Pathfinder digital Holter analysis system (Delmar Reynolds Medical Ltd) with manual review and editing. Data collected from the medical record included birth date, gender, coat color, body weight (BW), Holter date, length of Holter recording, total number of VPCs, couplets, triplets, salvos (> 4 VPCs in a row), ventricular tachycardia (VT) (> 5 VPCs in a row with rate > 100 bpm), bigeminy (pattern of alternating sinus beat and VPC), and number of VPCs displaying R on T (earliest VPCs). The numbers of the above events per hour (hr) were calculated by dividing the total number by the length of the recording. Date and manner of outcome was collected from the medical record or from phone calls to the owners or primary care veterinarians. Outcomes were obtained on 338 out of the 370 dogs. Outcomes were classified as SD, CHF, non-cardiac death, lost to follow-up, or still alive and asymptomatic as of May 1, 2007. Univariate and multivariate Cox proportional hazards analysis was used to determine if any Holter indices were predictive of the combined endpoint of SD or CHF. Dogs in the other outcome categories were censored. Significance level was P<0.05.

Of the 338 dogs, 58% were female and 42% were male. Median age and BW were 5.9 years (range 0.5-13.6) and 34.1 kg (range 22.7-57.5), respectively. Median Holter length was 22.8 hours. Percentage of asymptomatic dogs that had VPCs, couplets, triplets, salvos, VT, or bigeminy present were 68%, 24%, 12%, 10%, 7%, and 12%, respectively. 68 dogs (20%) experienced SD or CHF, while 270 (80%) were censored with a total of 168 dogs being still alive. On univariate analysis, many variables were directly associated with SD or CHF, including age, BW, VPCs/hr, VPCs with R on T/hr, couplets/hr, triplets/hr, presence of salvos, VT, and bigeminy. On multivariate analysis while accounting for age and BW, the variables that remained most significant in the face of combining variables were presence of salvos or VT, and bigeminy.

The presence of some degree of ventricular arrhythmia was found to be very common in a population of asymptomatic Dobermans, however this group may be very biased as it constitutes a voluntary group. The presence of salvos, VT, or bigeminy appears to be particularly significant in terms of prediction of potential for SD or CHF.

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Lynne O'Sullivan

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