Evaluation of a 5-Minute ECG in Comparison to the 24-Hour-ECG to Diagnose DCM in Doberman Pinschers
Dilated cardiomyopathy (DCM) in Doberman pinschers is characterized by a protracted, slowly progressive occult phase during which ventricular and occasionally atrial premature contractions first appear, followed by development of progressive left ventricular dysfunction and usually progressively more severe ventricular tachyarrhythmias. The incidence of sudden death, caused by ventricular tachycardia-fibrillation, prior to the onset of congestive heart failure (CHF) is at least 30%. Subsequent to CHF, death is usually the result of CHF but can occur suddenly. Diagnosis of the occult phase is based upon detection of more than 50 VPCs in a 24-hour ECG (Holter). Holter analysis requires special equipment, sufficient experience and is expensive, time consuming and is not always available.
The purpose of this study was to compare a 5-minute ECG to the Holter monitor results as a gold standard to diagnose occult cardiomyopathy in Doberman Pinschers.
A total of 498 Holter and 5-minute examinations of 324 Doberman Pinschers (53.1% female, 46.9% male) were compared for this study. Each dog was assessed by a 5-minute ECG, Holter examination and echocardiography at each examination. A cut-off value of >50 VPCs/24-hours on Holter examination was considered diagnostic for occult cardiomyopathy.
Holter examinations revealed >50 VPCs/24 hours in 123 examinations (24.7%). 61.8% of these examinations with >50 VES/24-hours had one or more VPCs in the 5-minute ECG. No VPCs in 5 minutes were found in 47 examinations, in which the Holter exam had diagnosed occult cardiomyopathy (38.2%). A 5-minute ECG with at least one VPC had a sensitivity of 61.8%, a specificity of 96.5%, a positive predictive value of 85.4% and a negative predictive value of 88.5% for the presence of >50 VES/24 hours.
Sensitivity of a 5-minute ECG is with 61.8% too low, to be a good screening test for occult Doberman Pinscher cardiomyopathy and can not replace a 24-hour ECG. Many dogs with >50 VPCs/24 hours had not even one VPC during 5 minutes. However, if at least one VPC is detected during a 5-minute ECG, the suspicion that the dog could have a cardiomyopathy should be high and the dog should be further assessed by a 24-hour Holter examination and echocardiography.