Long-term outcome of physiologic VDD pacing versus non-physiologic VVI pacing in dogs with high-grade atrioventricular block.

Objective: To compare the long-term outcome associated with physiologic VDD and non-physiologic VVI or VVIR pacing in dogs with high-grade atrioventricular block.

Animals: Forty-nine paced dogs with high-grade atrioventricular block were included.

Methods: Retrospective review of medical records, thoracic radiographs and echocardiograms for all dogs. Patient owners and referring veterinarians were contacted for survival times and a satisfaction questionnaire was submitted to the owners. Survival times, complication rates, resolution of clinical signs, and owner satisfaction were compared between the pacing modalities.

Results: A single lead VDD pacemaker was implanted in 19 dogs (39%) whereas 30 dogs (61%) were treated with VVI pacing. The median survival time for all dogs post-pacemaker implantation was 24.5 months. Survival time was significantly decreased in dogs that were older at the time of presentation or that presented with ventricular tachycardia or reduced left ventricular fractional shortening. Median survival times after implantation were not significantly different between pacing modalities (P = 0.29). Major complication rates were 11% within the VDD group and 20% within the VVI group and were not significantly different (P = 0.46). Minor complications were significantly higher within the VDD group than within the VVI group (47% versus 7% respectively; P < 0.01) due to a higher number of dogs in the VDD group experiencing transient ventricular premature contractions in the immediate post-implantation time period. Resolution of clinical signs, owner satisfaction, and quality of life perception were considered excellent in both groups.

Conclusions: No long-term clinical benefit of VDD over VVI pacing could be identified in the present study.