|Disease||QTc Interval||P-Wave||PR Interval||QRS Complex||ST-Segment Interval||T-Wave||Arrhythmias|
|Hypertrophic cardiomyopathy||Normal||(Left atrial enlargement)||Normal||Increased voltages in mid-left pre-cordial leads; abnormal “q” waves⁎ in inferior and/or lateral leads; (LAD, LBBB); (delta wave)||Down-sloping (up-sloping)||Inverted in mid-left pre-cordial leads; (giant and negative in the “apical” variant)||(Atrial fibrillation); (PVB); (VT)|
|Arrhythmogenic right ventricular cardiomyopathy/dysplasia||Normal||Normal||Normal||Prolonged >110 ms in right pre-cordial leads; epsilon wave in right pre-cordial leads; reduced voltages ≤0.5 mV in frontal leads; (RBBB)||(Up-sloping in right pre-cordial leads)||Inverted in right pre-cordial leads||PVB with an LBBB pattern; (VT with an LBBB pattern)|
|Dilated cardiomyopathy||Normal||(Left atrial enlargement)||(Prolonged ≥0.21 s)||LBBB||Down-sloping (up-sloping)||Inverted in inferior and/or lateral leads||PVB; (VT)|
|Myocarditis||(Prolonged)||Normal||Prolonged ≥0.21 s||(Abnormal “q” waves)⁎||Down- or up-sloping||Inverted in ≥2 leads||(Atrial arrhythmias); (PVB); (2nd or 3rd degree AV block); (VT)|
|Long-QT syndrome||Prolonged >440 ms in male subjects, >460 ms in female subjects||Normal||Normal||Normal||Normal||Bifid or biphasic in all leads||(PVB); (torsades de pointes)|
|Brugada syndrome||Normal||Prolonged ≥0.21 s||S1S2S3 pattern; (RBBB/LAD)||Up-sloping “coved-type” in right pre-cordial leads||Inverted in right pre-cordial leads||(Polymorphic VT); (atrial fibrillation) (sinus bradycardia)|
|Lenègre disease||Normal||Normal||Prolonged ≥0.21 s||RBBB; RBBB/LAD; LBBB||Normal||Secondary changes||(2nd or 3rd degree AV block)|
|Short-QT syndrome||Shortened <300 ms||Normal||Normal||Normal||Normal||Normal||Atrial fibrillation (polymorphic VT);|
|Pre-excitation syndrome (WPW)||Normal||Normal||Shortened <0.12 s||Delta wave||Secondary hanges||Secondary changes||Supraventricular tachycardia; (atrial fibrillation)|
|Coronary artery diseases†||(Prolonged)||Normal||Normal||(Abnormal “q” waves)⁎||(Down- or up-sloping)||Inverted in ≥2 leads||PVB; (VT)|
Less common or uncommon electrocardiography (ECG) findings are reported in parentheses.
AV = atrioventricular; LAD = left axis deviation of −30° or more; LBBB = left bundle branch block; RBBB = right bundle branch block; PVB = either single or coupled premature ventricular beats; QTc = QT interval corrected for heart rate by Bazett's formula; VT = either nonsustained or sustained ventricular tachycardia; WPW = Wolff-Parkinson-White.