In human cardiology, surface electrocardiography (ECG) is used for the risk stratification of patients affected by cardiomyopathies. The aim of the present study is to assess if ECG can show similar usefulness in cats with left ventricular hypertrophy (LVH).

Fifty-five privately owned cats (20 clinically healthy and 35 with LVH) were retrospectively selected. Complete physical examination, indirect measurement of arterial blood pressure, echocardiography, 2-minutes peripheral 6-lead ECG, and standard blood work, including serum thyroxine concentration were available. ECG measurements included: detection of any type of arrhythmia, heart rate, amplitude and duration of P wave and QRS complex, ST segment elevation or depression, mean electrical axis of P and T wave, and QRS complex, and PQ, QRS, QT, and QT corrected for heart rate (QTc) duration. In cats with LVH, outcome data and cause of death were annotated, when available.

Sinus rhythm was diagnosed in all healthy and in 24/35 (68.6%) cats with LVH. The remaining cats with LVH showed different types of rhythm disturbance, including third degree atrioventricular block (AVB) (2/35, 5.7%), sinus rhythm with isolated atrial (2/35, 5.7%) or ventricular ectopic complexes (2/35, 5.7%), sinus bradycardia (1/35, 2.9%), sinus rhythm associated with both first degree and second degree AVB (1/35, 2.9%), sinus rhythm associated with second degree AVB (1/35, 2.9%), accelerated idioventricular rhythm (1/35, 2.9%) and ventricular tachycardia (1/35, 2.9%). The presence of any type of arrhythmia had sensitivity of 31%, specificity of 100%, negative predictive value of 45%, and positive predictive value of 100%, in identifying LVH. ECG measurements were performed in all healthy cats and in 29/35 cats with LVH. Only QT and QTc were statistically different between healthy cats and cats with LVH (p<0.007 for both variables). Among the healthy cats, the highest values for QT and QTc were 180 ms, and 200 ms, respectively. Survival data were available for 23/29 cats with LVH where ECG measurements were performed. Of these 10/23 died for cardiac related cause. Median survival time was 58 days and not measureable for cats with QT>180 ms and QT≤180 ms, respectively, and 125 days and not measureable for cats with QTc>200 ms and QTc≤200 ms, respectively. Both QT>180 ms and QTc>200 ms were predictors of death for cardiac related causes (p=0.042 and p=0.017, respectively).

Surface ECG seems to provide useful diagnostic and prognostic information in cats with LVH.

Disclosures

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