Effect of severity of myocardial failure on heart rate variability in Doberman pinschers with and without echocardiographic evidence of dilated cardiomyopathy.

OBJECTIVE

To determine whether heart rate variability (HRV) is reduced in Doberman Pinschers with dilated cardiomyopathy.

DESIGN

Case series.

ANIMALS

62 overtly healthy Doberman pinschers.

PROCEDURE

Heart rate variability was analyzed in time and frequency domains from data obtained during 24-hour ambulatory electrocardiographic Holter recordings in 41 overtly healthy Doberman pinschers with normal echocardiograms and 21 overtly healthy Doberman pinschers with abnormal echocardiograms.

RESULTS

Heart rate variability usually was greater during night versus day, and 2 dogs with the most severe myocardial failure had reduced HRV.

CONCLUSIONS AND CLINICAL RELEVANCE

Reduced HRV was detected only in Doberman Pinschers with the most severe myocardial failure. Thus, HRV in less severely affected dogs is not reduced, or the normal sinus arrhythmia of dogs renders HRV relatively insensitive. Analysis of HRV did not provide additional information relative to the severity of left ventricular dysfunction or risk of sudden death from that which could be derived from echocardiography, analysis of Holter recordings, and signal-averaged electrocardiography.