Association between results of ambulatory electrocardiography and development of cardiomyopathy during long-term follow-up of Doberman pinschers.

Abstract

To characterize ambulatory electrocardiographic results of overtly healthy Doberman Pinschers and determine associations between those results and development of dilated cardiomyopathy. Cohort study. 114 (58 male, 56 female) overtly healthy Doberman Pinschers without echocardiographic evidence of cardiac disease on initial examination. Echocardiograms and 24-hour ambulatory electrocardiograms (Holter recordings) were obtained initially and at variable intervals. The status (live vs dead) of all dogs was known at least 2 years and as long as 10 years after initial examination (mean [+/- SD] follow-up time, 4.33 +/- 1.84 years). Associations between development of dilated cardiomyopathy and number of ventricular premature contractions (VPC), age, and sex were determined. 55 dogs (48%) did not have VPC on initial Holter recordings, and only 8 dogs had > 50 VPC/24 hours. The likelihood that a dog would have VPC was associated with increasing age and being male. At least 1 VPC/24 hours, and in particular, > 50 VPC/24 hours or > or = 1 couplet or triplet of VPC/24 hours, were predictive of subsequent development of dilated cardiomyopathy. Fifty-four dogs (47%) developed dilated cardiomyopathy; 12 were still alive at the end of the study, and 42 had died. Twenty-five of these 42 dogs died after the onset of congestive heart failure (CHF), 15 died suddenly before the onset of overt CHF, and 2 died of noncardiac causes. More males developed dilated cardiomyopathy than females, and dogs that died suddenly were approximately 1 year younger than those that developed CHF. Results of high-quality Holter recordings may be used to identify overtly healthy Doberman Pinschers that are at a high risk for dilated cardiomyopathy.