What is the small post‑QRS wave that may represent a normal variant?

Small Post-QRS Wave as a Normal Variant

The small wave after the QRS complex that may represent a normal variant is the J wave (also called Osborn wave), which appears as J-point elevation, terminal QRS slurring, or terminal QRS notching, and is part of the early repolarization pattern commonly seen in healthy young individuals and athletes. 1, 2

Definition and ECG Characteristics

The J wave is a deflection immediately following the QRS complex that can manifest in several forms 2, 3:

• Terminal QRS slurring: An abrupt change in the slope of the last deflection at the end of the QRS complex 1
• Terminal QRS notching: A low-frequency deflection at the end of the QRS complex, creating a notch appearance 1
• J-point elevation: When the J wave is partially buried in the R wave, it appears as elevation of the J point or ST-segment elevation 2, 4

The J point should be measured at the onset of the slur when present, or at the peak of the notch 1.

When This Is a Benign Normal Variant

In asymptomatic individuals, particularly young healthy subjects, athletes, and children, the early repolarization pattern with J waves is considered a normal variant requiring no further evaluation. 5, 6

Specific benign contexts include 5, 6, 4:

• Athletes: Isolated J-point elevation with terminal QRS slurring or notching and normal QRS duration is part of the normal spectrum of ECG findings 5
• Healthy young males: Early repolarization pattern is prevalent in this population with historically benign outcomes 6, 4
• Prevalence: Up to 10% of the general population demonstrates this pattern 1, 6

Critical Distinction: When to Be Concerned

While traditionally considered benign, recent evidence has identified specific patterns associated with increased arrhythmic risk 2, 6, 4:

High-Risk Features Requiring Further Evaluation

Type 2 pattern (inferior or inferolateral leads): Associated with higher risk for malignant arrhythmias 2, 4

Type 3 pattern (global distribution in inferior, lateral, and right precordial leads): Associated with highest risk and often linked to ventricular fibrillation storms 2, 4

Associated symptoms: Syncope, palpitations, or family history of sudden cardiac death elevates concern 1

Survivors of cardiac arrest: Terminal QRS slurring is found at significantly higher frequency in idiopathic ventricular fibrillation survivors compared to controls 1

Low-Risk Pattern (Benign Normal Variant)

Type 1 pattern (lateral precordial leads): Prevalent among healthy male athletes and rarely seen in ventricular fibrillation survivors 2, 4

Differential Diagnosis: What This Is NOT

Distinguish the benign J wave from pathological patterns 1:

• Brugada syndrome: Shows downward coved or saddleback ST-segment elevations specifically in leads V1-V3, associated with sudden cardiac death risk 1
• Epsilon waves: Low-frequency terminal QRS deflections in anteroseptal precordial leads seen in arrhythmogenic right ventricular cardiomyopathy 1
• RSR' pattern: Indicates right bundle branch block when QRS duration is prolonged (≥120 ms in adults), not a normal variant in that context 7, 5

Clinical Management Algorithm

For Asymptomatic Individuals with Type 1 Pattern (Lateral Leads)

No further cardiac workup is needed 5, 6. This represents a benign normal variant, particularly common in athletes and young males 5, 4.

For Patterns in Inferior or Inferolateral Leads (Type 2/3)

Even if asymptomatic, consider 1, 6:

• Complete cardiac evaluation to exclude structural heart disease
• Ambulatory ECG monitoring if arrhythmias are suspected 1
• Caution: Do not generate unnecessary anxiety, as the absolute risk remains low even with these patterns 6

For Any Pattern with Symptoms

Symptomatic patients (syncope, palpitations) or those with family history of sudden cardiac death require complete workup 1, 6:

• Ambulatory ECG monitoring to capture arrhythmias 1
• Echocardiography to assess structural heart disease
• Consider electrophysiology consultation for risk stratification

For Confirmed Early Repolarization Syndrome with Documented Ventricular Fibrillation

Implantable cardioverter defibrillator (ICD) insertion is clearly indicated 6.

Common Pitfalls to Avoid

• Misinterpreting technical artifacts as terminal QRS notching or slurring 1
• Confusing with myocardial infarction or pericarditis: The upward concavity of ST elevation in early repolarization differs from the morphology seen in acute coronary syndromes 8
• Generating excessive anxiety: The odds of developing malignant arrhythmias in asymptomatic individuals with isolated early repolarization pattern are extremely low 6
• Missing high-risk features: Failure to identify inferior/inferolateral distribution or associated symptoms that warrant further evaluation 1, 4