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 D oberman 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 Hotter r ecordings in 41 overtly healthy Doberman Pinschers with normal echocardiogr ams 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 Doberma n Pinschers with the most severe myocardial failure. Thus, HRV in less seve rely affected dogs is not reduced, or the normal sinus arrhythmia of dogs r enders HRV relatively insensitive. Analysis of HRV did not provide addition al 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.