Table 1

Criteria for a positive 12-lead ECG

P wave
 Left atrial enlargement: negative portion of the P wave in lead V1 ≥0.1 mV in depth and ≥0.04 s in duration
 Right atrial enlargement: peaked P wave in leads II and III or V1 ≥0.25 mV in amplitude
QRS complex
 Frontal plane axis deviation: right ≥+120° or left –30° to –90°
 Increased voltage: amplitude of R or S wave in a standard lead ≥2 mV, S wave in lead V1 or V2 ≥3 mV, or R wave in lead V5 or V6 ≥3 mV
 Abnormal Q waves ≥0.04 s in duration or ≥25% of the height of the ensuing R wave or QS pattern in two or more leads
 Right or left bundle-branch block with QRS duration ≥0.12 s
 R or R′ wave in lead V1 ≥0.5 mV in amplitude and R/S ratio ≥1
ST segment, T waves and QT interval
 ST-segment depression or T-wave flattening or inversion in two or more leads
 Prolongation of heart rate-corrected QT interval >0.44 s in males and >0.46 s in females
Rhythm and conduction abnormalities
 Premature ventricular beats or more severe ventricular arrhythmias
 Supraventricular tachycardias, atrial flutter or atrial fibrillation
 Short PR interval (<0.12 s) with or without “δ” wave
 Sinus bradycardia with resting heart rate ≤40 beats/min
 First- (PR >0.21 s), second- or third-degree atrioventricular block