Accuracy of 6-lead electrocardiography in identifying subclinical hypertrophic cardiomyopathy in cats

Background In people, electrocardiography (ECG) is recommended for screening of hypertrophic cardiomyopathy (HCM). Data for assessing the ability of ECG to screen HCM in apparently healthy cats is scarce. Hypothesis/Objectives Determine whether ECG variables on a 6-lead ECG can identify subclinical HCM in cats. Animals One hundred twelve cats were enrolled, 61 normal and 51 with subclinical HCM. Methods Single-center, cross-sectional study. Cats with normal hearts (end-diastolic left ventricular wall thickness [LVWTd] ≤ 5.0 mm) and cats with subclinical HCM (LVWTd ≥ 6.0 mm) were prospectively enrolled. Blinded assessment of the following ECG variables was performed: P wave amplitude and duration, PQ interval duration, amplitude of Q, R, and S waves, QRS duration, dispersion and mean electrical axis, R-to-peak time, T wave amplitude and duration, T/R ratio, T peak-to-end time (Tpte), Tpte/QT, RT concordance, QT interval (absolute and corrected for heart rate), presence of ST segment elevation (STE)/depression, and J wave. Results On multivariable analysis, a higher R wave amplitude (odds ratio [OR], 20.12; 95% confidence interval [CI], 2.4-227.5) and presence of STE (≥0.04 mV; OR, 8.3; 95% CI, 2.9-27.4) were the only variables independently associated with HCM after adjusting for body weight (area under the curve, 0.86; 95% CI, 0.78-0.93). An R wave amplitude > 0.26 mV as a sole screening test for HCM had 65% sensitivity and 62% specificity to detect HCM. Conclusions and clinical importance Our results suggest that a 6-lead ECG is a poor screening tool to detect subclinical HCM in cats.