Prominent J wave in cats with hypertrophic cardiomyopathy

The J wave has never been documented in the electrocardiogram (ECG) of cats presenting with hypertrophic cardiomyopathy (HCM). The present study aimed to describe the presence, morphology, amplitude, and duration of J waves in cats with HCM. It included 20 apparently healthy cats and 45 cats diagnosed with HCM based on clinical, echocardiographic, ECG, and radiographic examination. The cats were of different breeds (Persian: 40, domestic short hair: 21, Siamese: 4), ages (6.01 ± 4.34 years), sexes (male: 33, female: 32), and weights (3.30 ± 1.51 kg). The J wave was absent in the ECGs of the healthy population, but was detected in 29 out of 45 cats with HCM (63%). The J waves were observed at the QRS-ST junction in more than one limb lead of the ECG. Only positive deflections with an amplitude ≥0.05 mV were included, as measured by an ECG ruler in three consecutive heart cycles. The J waves were mainly present in leads II (n=20) and III (n=16), with amplitudes of 0.06 ± 0.02 and 0.08 ± 0.03 mV; their mean (± SD) duration was 0.16 ± 0.05 msec in lead II and 0.18 ± 0.05 msec in lead III. They occurred in both notched and slurred morphologies, with the latter being more common. In conclusion, J waves were a common finding in the ECGs of cats with HCM.