What is the management approach for a patient with an RSR (Ragged Red Spike) pattern on an electrocardiogram (ECG)?

Management of RSR' Pattern on ECG

An RSR' pattern on ECG requires systematic evaluation to distinguish benign variants from serious cardiac pathology, with management determined by the underlying cause—ranging from observation alone for incomplete right bundle branch block to urgent intervention for conditions like myocardial infarction or Brugada syndrome. 1

Initial Diagnostic Approach

First, verify technical accuracy by repeating the ECG with meticulous attention to lead placement, as precordial lead misplacement can create artifactual RSR' patterns that simulate pathology. 2 Ensure V1 and V2 are positioned in the fourth intercostal space at the right and left sternal borders, and V5-V6 at the horizontal extension of V4 in the fifth intercostal space. 2

Measure Key ECG Parameters

• QRS duration: Determine if <110 ms (normal), 110-119 ms (incomplete RBBB), or ≥120 ms (complete RBBB or other pathology) 1
• QRS axis: Calculate frontal plane axis to identify right axis deviation (90-180°), which suggests right ventricular pathology 1, 3
• R wave morphology in V1-V2: Identify the specific pattern (rSr', rsR', rSR', RSR') and measure R' amplitude 1
• S wave characteristics in lateral leads: Measure S wave duration in leads I and V6 (>40 ms suggests RBBB) 1

Differential Diagnosis Algorithm

1. Incomplete Right Bundle Branch Block (Most Common Benign Cause)

Diagnostic criteria: RSR' pattern with QRS duration 110-119 ms, normal R peak time in V5-V6, and S wave duration >40 ms in leads I and V6. 1 This represents delayed activation of the crista supraventricularis and is frequently a normal variant, especially in young adults and athletes. 4

Management: Observation without treatment in asymptomatic patients. 4 However, evaluate for atrial septal defect if there is fixed splitting of S2 on auscultation, as RBBB is common in ostium secundum ASD. 4

2. Complete Right Bundle Branch Block

Diagnostic criteria: QRS duration ≥120 ms with rsr', rsR', or rSR' in V1-V2, S wave duration >40 ms in leads I and V6, and R peak time >50 ms in V1. 1

Management approach:

• Asymptomatic patients with isolated RBBB: No pacing indicated; observation only 1
• Syncope with RBBB and HV interval ≥70 ms at electrophysiology study: Permanent pacing recommended 1
• Alternating bundle branch block (QRS alternating between RBBB and LBBB morphologies): Permanent pacing indicated due to high risk of complete heart block 1

3. Right Ventricular Hypertrophy/Overload

Diagnostic criteria: RSR' pattern with right axis deviation (>90°), tall R waves in V1 (as part of Rs, R, or Qr complexes), and ST depression with T-wave inversion in right precordial leads. 1, 5

Two distinct patterns:

• Pressure overload: Predominantly tall R waves in V1-V2, right axis deviation, ST depression and T-wave inversion in right precordial leads 1, 5
• Volume overload: RSR' pattern similar to incomplete RBBB with right axis deviation 1, 5

Management:

• Obtain echocardiography to assess right ventricular size, function, wall thickness, and estimated pulmonary artery pressure 2, 3
• Evaluate for underlying causes: Congenital heart disease, pulmonary hypertension, valvular disease, chronic lung disease 1
• Treat the underlying condition causing RV overload 3

4. Myocardial Infarction Scar

Diagnostic criteria: RSR' complex with QRS ≥110 ms in precordial leads (V1-V6) or inferior leads (II, III, aVF), unrelated to typical RBBB or LBBB patterns, associated with pathological Q waves. 6 An RSR' pattern in lateral leads (I, aVL, V5-V6) is particularly specific for ventricular aneurysm from extensive anterior-anterolateral scarring. 7

Management:

• Immediate echocardiography to assess for wall motion abnormalities (akinesis or dyskinesis) and left ventricular function 2, 6
• Consider cardiac catheterization if acute coronary syndrome suspected 1
• This pattern represents terminal conduction delay within impaired tissue surrounding infarct scar and has high specificity (though low sensitivity) for myocardial infarction 6

5. Brugada Syndrome (Life-Threatening)

Diagnostic criteria: RSR' pattern in V1-V2 with coved or saddleback ST-segment elevation ≥2 mm, particularly if QRS duration is normal or minimally prolonged. 8, 4

Management:

• Asymptomatic patients with Brugada pattern: Observation without treatment 1
• Cardiac arrest or sustained ventricular arrhythmia: ICD implantation if meaningful survival >1 year expected 1
• Avoid triggers: Fever (treat aggressively), certain medications (psychotropics, anesthetics), cocaine, excessive alcohol 1
• Genetic testing: May facilitate family screening but negative test does not exclude diagnosis 1

6. Early Repolarization Pattern

Diagnostic criteria: RSR' pattern with J-point elevation ≥0.1 mV in inferior or lateral leads. 1

Management:

• Asymptomatic patients without family history of sudden cardiac death: Observation only; further evaluation not recommended 1
• Cardiac arrest or ventricular fibrillation: ICD implantation 1
• Unexplained syncope with family history of sudden death: Consider comprehensive arrhythmia evaluation 1

7. Arrhythmogenic Right Ventricular Cardiomyopathy

Diagnostic criteria: RSR' pattern in V1-V3 with epsilon waves (small deflections after QRS), T-wave inversion in right precordial leads, and ventricular arrhythmias of LBBB morphology. 8, 4

Management: Requires specialized cardiac imaging (cardiac MRI), genetic testing, and consideration for ICD placement based on risk stratification. 8

Special Clinical Scenarios

Chronic Obstructive Pulmonary Disease

ECG pattern: Low voltage in limb leads, rightward/superior/indeterminate QRS axis, rightward P-wave axis (>60°), persistent S waves in all precordial leads, low R wave amplitude in V6. 1, 5 RVH is suggested only if R wave amplitude in V1 is relatively increased in this context. 5

Athletes

Incomplete RBBB is common and benign in athletes unless accompanied by family history of sudden cardiac death, symptoms, or left ventricular hypertrophy. 2, 4 If isolated without other abnormalities, no further workup required. 2

Pediatric Patients

Age-specific criteria must be applied, as normal QRS axis in neonates ranges from 55-200° and gradually shifts leftward with age. 3 By 1 month, normal upper limit is ≤160°. 3

Critical Pitfalls to Avoid

• Do not dismiss RSR' as benign without systematic evaluation, as it can represent life-threatening conditions like Brugada syndrome or myocardial infarction 8, 6
• Do not apply adult criteria to pediatric patients, as this leads to overdiagnosis of right axis deviation 3
• Do not overlook biventricular hypertrophy when RSR' pattern coexists with LVH criteria—look for prominent S waves in V5-V6 and right atrial abnormality 1, 5
• Do not ignore fixed splitting of S2 on exam, as this suggests atrial septal defect even with benign-appearing incomplete RBBB 4
• Verify lead placement before attributing RSR' to pathology, as high placement of V1-V2 or pectus excavatum can create artifactual patterns 4