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

Abstract

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 ($\ge$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.