Early Repolarization Pattern and Terminal QRS Slur

Definition and ECG Characteristics

The American Heart Association defines terminal QRS slur as an abrupt change in the slope of the last deflection at the end of the QRS, distinguishing it from a terminal QRS notch 1, 2
The J point should be measured at the onset of the slur when present, as part of the early repolarization pattern (ERP) which can include ST-segment elevation or terminal QRS notching 2
ERP can include ST-segment elevation without chest pain, terminal QRS slurring, or terminal QRS notching, with the slur considered part of the QRS complex itself 3, 4

Terminal QRS slurring has been associated with increased risk of idiopathic ventricular fibrillation and sudden cardiac arrest, with a prevalence of up to 10% in the general population 1, 4
The pattern resembles Brugada syndrome in arrhythmogenicity under certain conditions, and survivors of idiopathic sudden cardiac arrest demonstrate terminal QRS slurring at significantly higher frequency than controls 3, 4
The American College of Cardiology recommends differentiating terminal QRS slurring from Brugada pattern, which shows downward coved or saddleback ST-segment elevations in leads V1-V3, associated with sudden cardiac death 2

Terminal QRS slurring should be differentiated from epsilon waves, which are low-frequency terminal QRS deflections in anteroseptal precordial leads seen in arrhythmogenic right ventricular cardiomyopathy, and from fragmented QRS, which suggests myocardial scar with high specificity 2
J-point elevation ≥1 mm, when present with inferior or lateral lead distribution, may increase risk, and should be considered in the evaluation of terminal QRS slurring 1, 2

A terminal QRS notch is defined as a low-frequency deflection at the end of the QRS complex, initially described by Osborn as J waves, referring to injury 5
QRS notching is part of the early repolarization pattern, which is an umbrella term that can refer to ST-segment elevation in the absence of chest pain, terminal QRS slur, or terminal QRS notch 6
The J point should be measured with the peak representing the peak of the notch or onset of a slur when present 7

Early repolarization pattern with QRS notching was originally considered a normal variant with a benign outcome, with prevalence as high as 10% in the general population 8
More recent studies have demonstrated associations between certain patterns of QRS notching and adverse outcomes, including idiopathic ventricular fibrillation and sudden cardiac death 9

Assess for other ECG abnormalities that may indicate specific cardiac pathologies 8
Distinguish between terminal QRS notching and other similar patterns, such as epsilon waves seen in arrhythmogenic right ventricular cardiomyopathy, and Brugada pattern characterized by downward coved and saddleback ST-segment elevations 7

Association with symptoms such as syncope, palpitations, or family history of sudden cardiac death is a higher risk feature 10

Misinterpreting technical artifacts as QRS notching 5
Failing to distinguish between benign early repolarization and potentially pathological QRS notching patterns 9

RSR' pattern indicates right bundle‑branch block when the QRS duration is ≥120 ms in adults and should not be interpreted as a normal J‑wave variant. The American College of Cardiology clarifies this distinction. 11

For individuals displaying type 2 or type 3 early‑repolarization patterns (inferior or inferolateral leads) – even if they have no symptoms – the ACC recommends a complete cardiac evaluation to rule out structural heart disease, which includes echocardiographic imaging. 11
When patients present with syncope, palpitations, or a family history of sudden cardiac death, the ACC advises a comprehensive work‑up that incorporates ambulatory ECG monitoring and echocardiography to detect occult arrhythmias or structural abnormalities. 11