Abstract: Background – T-wave peak-end to QT ratio (TpTe:QT) is an electrocardiographic measure of myocardial repolarization shown to predict DCM in Doberman Pinschers. The possible role of TpTe:QT in predicting clinically relevant arrhythmogenesis and sudden cardiac death has not been previously studied.
Hypothesis/Objectives – TpTe:QT is increased in Doberman Pinschers that later develop clinically relevant ventricular arrhythmias and/or sudden cardiac death.
Animals – 30 Doberman Pinschers with 24-hour ambulatory ECG and echocardiogram cardiovascularly healthy at screening and followed for a median of 3.9 years.
Methods – Ambulatory ECG data were manually evaluated by a blinded investigator. TpTe was measured from the peak to the end of the T wave using the tangent method, TpTe:QT was calculated and measurements were averaged from three sinus beats at median heart rate periods. Univariate Cox regression analyses were performed for variables of interest, including echocardiographic parameters and 24-hour Holter ECG data.
Results – Of 30 dogs, 8 required antiarrhythmic drug intervention and 2 died suddenly during the follow-up period. Ventricular ectopy was significantly associated with the outcome (hazard Ratio 1.09 per 100 VPCs/day; 95% CI, 1.02–1.07; P = 0.001). TpTe:QT ratio did not reach significance (P=0.057; hazard ratio: 1.50 per 0.01 unit) but remains of interest given the probability of type II error.
Conclusions and Clinical Importance – Ventricular ectopy recorded at time of first Holter are indicative of need for future anti-arrhythmic medication and sudden cardiac death in Doberman Pinschers. Prospective studies should investigate the role of TpTe:QT in predicting disease outcomes.
