Use of a spot-check protocol to measure ventricular response rate in dogs with atrial fibrillation

INTRODUCTION/OBJECTIVES: Fast ventricular response rates (VRRs) have negative prognostic value in atrial fibrillation (AF). Therapeutic recommendations for canine AF rely on measurements of VRR from ambulatory electrocardiograms (aECGs). ANIMALS, MATERIALS AND METHODS: Data from aECG of dogs with AF were prospectively acquired alongside VRR measurements obtained at home using a smartphone-based ECG device between 7:00 and 23:00. From these data, three protocols were outlined: (A) three eight-hourly spot-checks, (B) three six-hourly spot-checks, and (C) five predetermined spot-checks. The performance of the protocols was compared with aECG using mesor, mean and median VRR. The presence of circadian variation was explored using cosinor analysis. RESULTS: Eighteen aECGs were analysed, and 14 were used to test the spot-check protocols. The protocols showed moderate to strong correlation with aECG, with protocol B performing best (mean, r = 0.84, P=<0.0001, bias -22.96, limits of agreement 24.4; median, r = 0.90, P<0.0001, bias -24.48, limits of agreement 22.04). Using a mean VRR <125 beats per minute (bpm) as cut-off, 10 of 14 dogs (71.4%) had inadequate VRR control. All protocols correctly identified these dogs, with protocol A performing best for mean VRR >140 bpm. Circadian variation in VRR was identified in 17 of 18 dogs (94%). LIMITATIONS: This study is limited by the small population, highly prevalent inadequate VRR, non-standardised treatment, measurement artefacts and precise temporal alignment with aECG. CONCLUSIONS: Spot-check protocols offer a practical, affordable alternative to aECG for VRR assessment in dogs with AF. A mean VRR >140 bpm in the protocol predicts inadequate rate control on aECG.