(C31) Asymptomatic Arrhythmias in Aged, Apparently Healthy Dogs Screened for a Large, Multi-center Clinical Trial

Abstract:

Background: Clinically relevant arrhythmias can occur in dogs without overt clinical signs. Arrhythmias have been previously established as important exclusionary criteria from the Test of Rapamycin in Aging Dogs (TRIAD).

Hypothesis/

Objective: Describe the nature and prevalence of clinically significant arrhythmias and concurrent abnormalities at screening within the TRIAD target population.

Animals: Reportedly healthy dogs ≥ 7 years of age and 20-55 kg (n=247) assessed for eligibility within the multi-center TRIAD clinical trial.

Methods:
Cross-sectional assessment of dogs qualified for in-person screening examination after medical record review. Examination included systolic arterial blood pressure, physical examination, five-minute electrocardiogram, complete echocardiogram, CBC, chemistry, urinalysis, heartworm serology for all dogs with Chagas IFA testing for dogs in Texas. Holter monitoring was introduced to evaluate ventricular ectopy (VE) identified during screening that did not warrant antiarrhythmic therapy.

Results:
38/235 (16%) screened dogs (18 F/S; 20 M/C) had VE and 24/38 (63%) had a Holter performed. Of those 24 dogs, 8 remained eligible and 16 were excluded from enrollment in the TRIAD study based on the complexity of arrhythmias on Holter. Exclusionary arrhythmias found on Holter included ventricular tachycardia (6/16), ventricular couplets/triplets (3/16), and ≥50 VPCs in 24hrs (7/16). Concurrent findings in some dogs excluded with arrhythmias included neoplasia, cardiac disease, positive Chagas titer, and biochemical changes.

Conclusions and Clinical Importance:
Clinically significant VE is common within this age group of medium-to-large dogs, even when seemingly healthy upon records review. When VE is encountered upon physical examination, Holter monitoring can reveal increased arrhythmia severity.