What does poor R wave progression on an electrocardiogram (ECG) mean?

Poor R-Wave Progression: Clinical Significance and Interpretation

Poor R-wave progression (PRWP) on an electrocardiogram (ECG) primarily indicates a failure of the normal increase in R-wave amplitude across the precordial leads (V1-V6), which may represent anterior myocardial infarction but has multiple other potential causes requiring careful clinical evaluation.

Definition and Recognition

• PRWP is characterized by the failure of the expected increase in R-wave amplitude from leads V1 through V5 1
• Superior misplacement of V1 and V2 electrodes in the second or third intercostal space (rather than the fourth) can cause reduction in initial R-wave amplitude, approximating 0.1 mV per interspace, resulting in PRWP 1
• The Marquette criteria define PRWP as R-wave amplitude ≤0.3 mV in lead V3 and R-wave amplitude in lead V2 ≤ R-wave amplitude in lead V3 2, 3

Clinical Significance and Differential Diagnosis

PRWP has four major potential causes:

1. Anterior Myocardial Infarction

   • PRWP may indicate prior anterior myocardial infarction, particularly when accompanied by pathological Q waves 1, 4
   • In patients with PRWP and normal QRS axis, there is a significant association with non-ST-elevation myocardial infarction (NSTEMI) 4

2. Electrode Misplacement

   • Superior displacement of V1 and V2 electrodes can result in rSr' complexes with T-wave inversion, resembling the complex in lead aVR 1
   • Precordial lead misplacement explains considerable variability in amplitude measurements between serial tracings 1

3. Pulmonary Conditions

   • In patients with low diaphragm position (e.g., obstructive pulmonary disease), V3 and V4 may be located above ventricular boundaries and record negative deflections that simulate anterior infarction 1

4. Normal Variant

   • PRWP can be a normal variant, particularly in individuals with a low cardiothoracic ratio 3
   • The positive predictive value of PRWP for coronary artery disease in the general population is low (approximately 7.3%) 3

Prognostic Implications

• PRWP is associated with increased risk of sudden cardiac death (hazard ratio 2.13), cardiac death (hazard ratio 1.75), and all-cause mortality (hazard ratio 1.29) in the general population 2
• The association with sudden cardiac death is particularly strong in subjects with coronary artery disease (hazard ratio 2.62) 2
• PRWP is present in approximately 3.1% of the general population 2

Related ECG Findings

• Reversed R-wave progression (RRWP): Defined as RV2 < RV1, RV3 < RV2, or RV4 < RV3, is rarer (0.3% prevalence) but more specific for cardiac disease 5
• RRWP is highly associated with ischemic heart disease, particularly left anterior descending artery stenosis 5
• When evaluating PRWP, attention should be paid to the QRS axis, as PRWP with a normal QRS axis has stronger association with myocardial infarction 4

Evaluation Approach

When PRWP is identified on ECG:

1. Check electrode placement

   • Ensure proper positioning of precordial leads, particularly V1 and V2 in the fourth intercostal space 1
   • Improper electrode placement can cause artifactual PRWP 1

2. Look for associated ECG findings

   • Presence of pathological Q waves (Q/R ratio ≥0.25 or ≥40 ms in duration in two or more contiguous leads) 1
   • QRS axis (normal axis with PRWP increases likelihood of myocardial infarction) 4
   • ST-segment depression (≥0.5 mm in two or more contiguous leads) suggests myocardial ischemia rather than normal variant 1

3. Consider clinical context

   • Age, cardiac risk factors, symptoms, and history of cardiac disease 2
   • Presence of heart failure, coronary artery disease, or use of β-blocker medication increases likelihood of pathological PRWP 2

4. Further cardiac evaluation when indicated

   • Echocardiography to assess for wall motion abnormalities or cardiomyopathy 1
   • Consider cardiac MRI if echocardiogram is inconclusive but clinical suspicion remains high 1
   • In patients ≥30 years with risk factors for coronary artery disease, stress testing may be warranted 1

Pitfalls and Caveats

• PRWP alone has a low positive predictive value for coronary artery disease in asymptomatic individuals 3
• Electrode placement significantly affects R-wave progression; improper placement can lead to false positive findings 1
• In women with large breasts, electrode placement (under vs. over breast tissue) can affect R-wave amplitude and progression 1
• Day-to-day variability in electrode placement can limit reproducibility of ECG findings 1