Determining the optimal Holter monitoring duration for detecting ventricular arrhythmia in dogs: a Bayesian approach

The objective of this study was to determine the optimal duration of ambulatory electrocardiography (Holter) monitoring for detecting ventricular arrhythmias (VAs) and to assess day-to-day spontaneous variability in dogs using seven-day recordings.

Medical records of dogs undergoing the consecutive seven-day Holter monitoring were retrospectively reviewed. Dogs were included if the Holter monitoring was performed for collapse, arrhythmia-related symptoms, or documented VAs on prior electrocardiography. Dogs undergoing routine breed screening or evaluated for bradyarrhythmias or supraventricular tachycardia were excluded. Day-to-day variability in VA burden was assessed using the percent coefficient of variation (CV%). Bayesian probability modeling was used to analyze arrhythmia detection from days one through seven, identifying the point at which additional monitoring provided diminishing diagnostic returns.

Of 124 Holter recordings reviewed, 87 met inclusion criteria. The percent coefficient of variation (CV%) for daily ventricular premature complex (VPC) frequency ranged from 8 to 188%. Bayesian analysis showed that detection of >1000 VPCs, >500 VPCs, or ventricular tachycardia episodes increased within the first three days of monitoring, with minimal improvement thereafter. Detection of >100 VPCs plateaued after two days. R-on-T VPCs exhibited continued detection increases through days four to five. Dogs receiving anti-arrhythmic drugs plateaued by day 3, whereas untreated dogs showed continued detection increases up to day 5.

The study's retrospective nature, modest sample size for treated dogs, and variability in anti-arrhythmic protocols may limit generalizability.

A three-day Holter monitoring duration is recommended for detecting most VAs in dogs, while four days may be required for R-on-T event detection.