Table 2.

Electrocardiographic markers linked to SCD risk in the general population and potential pathophysiologic mechanisms

ECG marker	Possible mechanism(s)
Resting heart rate	?Increased sympathetic tone
Abnormalities of depolarization
Pathologic Q waves/QRS score	Myocardial scar, LV dysfunction, re-entrant arrhythmia
QRS duration	Prolonged depolarization–?facilitation of re-entry
QRS fragmentation	Fibrosis, inhomogeneous myocardial conduction, re-entry
Increased myocardial voltage (ECG-LVH)	?Increased LV mass ?Other abnormal electrical remodelling
Abnormalities of repolarization
QTc/JTc	Prolonged repolarization
QT/JT dispersion	Heterogeneity of repolarization, ?Phase 2 re-entry
T-peak to T-end interval	Transmural dispersion of repolarization
Early repolarization pattern	?Phase 2 re-entry
QRS–T angle	Abnormal depolarization, heterogeneity of repolarization

SCD, sudden cardiac death; ECG, electrocardiogram; LV, left ventricular; LVH, left ventricular hypertrophy; QTc/JTc, corrected QT/JT interval.