What is the clinical significance and management of notched R waves on an electrocardiogram (ECG) in patients with a history of hypertension, coronary artery disease, or other cardiovascular conditions?

Notched R Waves on ECG: Clinical Significance and Management

Notched R waves on ECG have distinct clinical significance depending on their location, QRS duration, and clinical context—ranging from benign normal variants to markers of serious cardiac pathology including prior myocardial infarction, bundle branch blocks, and structural heart disease.

Differential Diagnosis by Lead Location

Notched R Waves in Precordial Leads V1-V2

Right Bundle Branch Block (RBBB)

The most common pathological cause of notched R waves in V1-V2 is RBBB, which requires specific diagnostic criteria 1:

• Complete RBBB: QRS duration ≥120 ms in adults with rsR', rSR', or RSR' pattern in V1 or V2, where the R' deflection is typically wider than the initial R wave 1
• Incomplete RBBB: Same morphology but QRS duration 110-119 ms in adults 2, 3
• Additional supporting criteria include S wave duration >40 ms in leads I and V6, and R peak time >50 ms in V1 1

Normal Variant (Critical Distinction)

• In children, an rsR' pattern in V1-V2 with normal QRS duration (<120 ms) is a normal variant and requires no further evaluation 1, 2
• In athletes, isolated rsR' pattern with normal QRS duration is part of the normal ECG spectrum 2
• Approximately 7-8% of normal adults may demonstrate this pattern without underlying disease 4

Right Ventricular Hypertrophy

• Can present with notched R waves in V1-V2, particularly when associated with right axis deviation 2
• Consider in patients with chronic pulmonary disease, pulmonary hypertension, or congenital heart disease 1

Notched R Waves in Lateral Leads (I, aVL, V5-V6)

Left Bundle Branch Block (LBBB)

• Broad notched or slurred R waves in leads I, aVL, V5, and V6 with QRS duration ≥120 ms in adults 1
• Absent q waves in I, V5, V6 (narrow q may be present in aVL) 1
• R peak time >60 ms in V5-V6 1

Notched R Waves in Inferior Leads (II, III, aVF)

"Crochetage" Pattern—Highly Specific for Atrial Septal Defect

• A notch near the apex of the R wave in inferior limb leads has 73% sensitivity for secundum atrial septal defect 5
• When present in all three inferior leads, specificity exceeds 92% for atrial septal defect 5
• Correlates with shunt severity and defect size 5
• This pattern is independent of RBBB and may disappear after surgical repair while RBBB persists 5

Fragmented QRS Complex: Marker of Myocardial Scar

Critical for Patients with Coronary Artery Disease or Hypertension

Fragmented QRS (fQRS) includes various RSR' patterns with QRS <120 ms, showing additional R waves, notching in the S wave nadir, or multiple R' waves in two contiguous leads corresponding to coronary territories 6:

• Sensitivity for prior MI: 85.6% compared to only 36.3% for Q waves alone 6
• Negative predictive value: 92.7% for excluding myocardial scar 6
• Represents altered ventricular depolarization from prior myocardial scarring 6
• In patients with known CAD or hypertension presenting with notched R waves, actively search for fQRS pattern as it substantially outperforms Q waves for detecting prior infarction 6

Clinical Management Algorithm

Step 1: Measure QRS Duration

If QRS ≥120 ms:

• Apply complete bundle branch block criteria 1
• RBBB if rsR' in V1-V2 with appropriate supporting criteria 1
• LBBB if broad notched R in I, aVL, V5-V6 with absent q waves 1
• Consider echocardiography to assess ventricular function and structural disease 1

If QRS <120 ms:

• Proceed to Step 2 for pattern recognition 2, 6

Step 2: Identify Specific Patterns

Fragmented QRS (notching with additional R waves in coronary territories):

• High suspicion for prior MI in patients with CAD risk factors or hypertension 6
• Order myocardial perfusion imaging or cardiac MRI to assess for scar 6
• Initiate or optimize secondary prevention for coronary disease 6

Crochetage in all three inferior leads:

• Order transthoracic echocardiography with bubble study to evaluate for atrial septal defect 5
• Specificity >92% when present in all inferior leads 5

rsR' in V1-V2 only (normal QRS duration):

• In children or athletes: benign normal variant, no further workup needed 1, 2
• In adults with cardiovascular risk factors: consider echocardiography if other abnormalities present 2

Step 3: Context-Specific Evaluation

Hypertension:

• Assess for left ventricular hypertrophy using voltage criteria 1
• Notched R waves in lateral leads may indicate LVH with strain 1
• Echocardiography recommended for definitive assessment 1

Known or Suspected CAD:

• Fragmented QRS pattern mandates evaluation for myocardial scar 6
• Consider stress testing or advanced imaging 6
• Reversed R wave progression (RV2<RV1, RV3<RV2, or RV4<RV3) is rare (0.3%) but highly specific (76%) for cardiac disease, particularly LAD stenosis 7

Pulmonary Disease:

• Notched R in V1-V2 may indicate right ventricular hypertrophy 1
• Correlate with right axis deviation and right atrial abnormality 1

Critical Pitfalls to Avoid

• Do not dismiss rsR' pattern in V1-V2 as "incomplete RBBB" without measuring QRS duration—normal QRS duration indicates a benign variant in most cases 1, 2
• Do not rely solely on Q waves to detect prior MI—fragmented QRS has 2.4-fold higher sensitivity 6
• Lead misplacement can create false positive or false negative findings—verify proper electrode placement, particularly with superior/inferior displacement 4
• In patients with LBBB, diagnosis of LVH should be made with caution due to conflicting evidence 1
• Crochetage pattern is often overlooked—actively search inferior leads in patients with unexplained dyspnea or murmurs 5