Table 1 Definition of abnormal ECG findings

Left atrial enlargement

Negative portion of the P wave in lead V1 ≥ 0.1 mV in depth and ≥ 40 msec in duration

Right atrial enlargement

P-wave amplitude ≥ 0.25 mV in leads II, III or aVF

Left QRS-axis deviation

-30^O to -90^O

Right QRS-axis deviation

> 115^O

Right ventricular hypertrophy

Sum of R wave in V1 and S wave in V5 or V6 ≥ 10.5 mm

Complete LBBB

QRS ≥ 120 msec predominantly negative QRS complex in lead V1 (QS or rS), and upright monophasic R wave in leads I & V6

Complete RBBB

RSR’ pattern in anterior precordial leads with QRS duration ≥ 120 msec

Intraventricular conduction delay

Any QRS duration > 120 msec including RBBB and LBBB

Pathological Q-wave

>-0.4 mV in any lead except III, aVR or a Q/R ratio ≥ 0.25

T-wave inversion

≥-0.1 mV in ≥ 2 contiguous leads other than in leads V1, aVR and III

ST-segment depression

≥ 0.5 mm deep in ≥ 2 leads

Ventricular pre-excitation

PR interval < 120 msec with delta wave