What is the management and treatment approach for a patient with a possible right ventricular conduction delay indicated by an RSR (QR) pattern in leads V1/V2 on the electrocardiogram (ECG)?

Management of RSR' (QR) Pattern in V1/V2

In asymptomatic patients with an RSR' pattern in V1/V2, measure the QRS duration: if <110 ms, reassure and provide routine follow-up; if 110-119 ms (incomplete RBBB), monitor annually for progression; if ≥120 ms (complete RBBB), obtain an echocardiogram to evaluate for structural heart disease and monitor for development of higher-degree conduction disorders. 1

Initial ECG Assessment

The RSR' pattern in leads V1-V2 is characterized by an initial small r wave, followed by an S wave, and then a terminal R' (r') deflection that is typically wider than the initial r wave 2. The critical first step is measuring the QRS duration to categorize the finding 1:

• QRS <110 ms: Likely normal variant or nonspecific finding 1
• QRS 110-119 ms: Incomplete right bundle branch block (RBBB) 2, 1
• QRS ≥120 ms: Complete RBBB requiring further evaluation 2, 1

Symptom Evaluation

Assess specifically for 1:

• Syncope or presyncope (suggests possible high-grade conduction disease or arrhythmia)
• Palpitations (may indicate associated arrhythmias)
• Dyspnea or exercise intolerance (suggests possible structural heart disease or cardiac dyssynchrony)
• Family history of sudden cardiac death or inherited arrhythmia syndromes (raises concern for Brugada syndrome or arrhythmogenic conditions)

Differential Diagnosis Beyond Simple RBBB

While incomplete or complete RBBB is the most common cause of RSR' in V1/V2 1, critical alternative diagnoses include:

• Brugada syndrome: Distinguished by coved ST-segment elevation ≥2 mm with terminal T-wave inversion in V1-V2 1. The Corrado index (STJ/ST80 ratio >1) helps differentiate Brugada pattern from benign RSR' 1
• Arrhythmogenic right ventricular dysplasia: Consider in younger patients with symptoms 3
• Right ventricular infarction/ischemia: May show "cove-shaped" ST-T elevation in V1 during hyperacute phase 4
• Normal variant: Common in young, healthy individuals, particularly when QRS <110 ms 3, 5

Management Algorithm by QRS Duration

QRS Duration <110 ms (Normal Variant)

• No specific treatment required 1
• Provide reassurance
• Routine follow-up only 1
• Verify correct lead placement to exclude technical error 1

QRS Duration 110-119 ms (Incomplete RBBB)

• Annual follow-up to monitor for progression 1
• Document baseline ECG for comparison
• Consider echocardiogram if symptoms present (heart failure, arrhythmia) 1
• Monitor for development of complete RBBB, which occurs in a subset of patients 5

Key ECG features suggesting true incomplete RBBB rather than normal variant 5:

• SV1/SV2 ratio >1.0 (inverted S wave depth ratio)
• Slurring of S wave downstroke or upstroke
• Diminution of S wave depth in V1
• Patient age >50 years

QRS Duration ≥120 ms (Complete RBBB)

• Obtain echocardiogram to evaluate for structural heart disease 1
• Monitor for development of higher-degree conduction disorders 1
• Assess for cardiac dyssynchrony if heart failure symptoms present 2
• Consider underlying causes: coronary disease, cardiomyopathy, congenital heart disease 2

Indications for Electrophysiology Referral

Refer to electrophysiologist if 1:

• Brugada pattern identified (coved ST elevation ≥2 mm in V1-V2)
• Syncope or presyncope episodes
• Family history of sudden cardiac death
• Evidence of progressive conduction disease (e.g., development of AV block)
• Concern for arrhythmogenic right ventricular dysplasia

Common Pitfalls

Avoid misdiagnosing Brugada syndrome: The RSR' pattern alone without coved ST elevation and T-wave inversion is not Brugada syndrome 1. Use the Corrado index when uncertain 1.

Don't overlook progression: Incomplete RBBB can progress to complete RBBB, particularly in older patients with SV1/SV2 ratio >1.0 5. Annual monitoring is essential 1.

Verify lead placement: An apparent RSR' pattern may result from incorrect electrode positioning 1. Confirm with repeat ECG if morphology seems atypical.

Consider age and context: In young, asymptomatic individuals with QRS <110 ms, this is typically a benign normal variant requiring only reassurance 3, 5. In older patients or those with structural heart disease, more thorough evaluation is warranted 5.