Research Fellow North Carolina State University Yokohama-city, Kanagawa, Japan
Abstract:
Background: The T-wave peak-to-end to QT ratio (TpTe:QT) is an electrocardiographic marker of myocardial repolarization dispersion that is not influenced by the RR interval. Hypothesis/
Objectives: The authors hypothesized that TpTe:QT is prolonged in Doberman Pinschers (DPs) with dilated cardiomyopathy (DCM). Animals: Thirty-five client-owned DPs.
Methods: This retrospective cross-sectional study included clinically healthy DPs that are PDK4 and/or TTN genotype positive as the controls, and DPs diagnosed with subclinical DCM (no history of congestive heart failure) as the DCM+ group. Dogs receiving antiarrhythmic drugs were excluded. Using ambulatory electrocardiograms, QT interval, QTc, TpTe, TpTe:QT, and corrected TpTe were measured as repolarization markers. Risk ratios for identifying the DCM phenotype, and interrelationships among RR interval, DCM phenotype, and each marker were evaluated.
Results: Twelve dogs were classified as DCM+ group, and 23 were classified as controls. TpTe:QT was significantly higher in the DCM+ group compared to controls (risk ratio 1.23), with negligible to weak correlation identified to RR interval. TpTe and corrected TpTe were also elevated in the DCM+ group (risk ratios 1.04 and 1.06, respectively), however, these values were significantly influenced by RR interval. Conclusions and clinical importance: TpTe:QT is a potential marker for distinguishing Doberman Pinschers with subclinical DCM from those that are normal yet genetically at risk. Its independence from heart rate variation underscores its potential utility in clinical practice. TpTe:QT is a simple, non-invasive, and readily available test that may predict subclinical DCM in DPs.
