What is the significance of poor R wave progression on an electrocardiogram (ECG) in adults with risk factors for cardiovascular disease?

Poor R Wave Progression: Clinical Significance

Poor R wave progression (PRWP) on ECG is most commonly caused by technical factors—particularly electrode misplacement—but when true, it indicates one of four distinct entities: anterior myocardial infarction, left ventricular hypertrophy, right ventricular hypertrophy, or a normal variant with diminished anterior forces. 1, 2

Definition and Recognition

• PRWP is characterized by failure of the expected increase in R-wave amplitude from leads V1 through V5 1
• The commonly used diagnostic criterion is R-wave amplitude ≤2 mm in leads V3 or V4 3
• Reversed R wave progression (RRWP)—defined as RV2 < RV1, RV3 < RV2, or RV4 < RV3—is more specific for cardiac pathology, with 76% association with cardiac disease 4, 5

Critical First Step: Exclude Technical Causes

Before attributing PRWP to cardiac pathology, you must verify proper electrode placement, as this is the most frequent cause of apparent PRWP. 1, 5

• Superior misplacement of V1 and V2 electrodes (in the second or third intercostal space instead of the fourth) reduces R-wave amplitude by approximately 0.1 mV per interspace, creating artifactual PRWP 6, 1
• This misplacement can produce rSr' complexes with T-wave inversion resembling lead aVR 6, 1
• Inferior-leftward misplacement of left precordial electrodes occurs in more than one-third of routine ECGs 1
• Lead placement variability as little as 2 cm can result in diagnostic errors regarding anteroseptal infarction 1, 5
• Always repeat the ECG with meticulous attention to proper lead placement: V1 and V2 in the fourth intercostal space at the sternal border, V4 in the fifth intercostal space at the midclavicular line, and V5-V6 at the horizontal extension of V4 5

The Four Major Pathological Causes

1. Anterior Myocardial Infarction (Most Clinically Significant)

• This is the most critical diagnosis to identify, particularly when PRWP is accompanied by pathological Q waves 1, 6
• Pathological Q waves are defined as Q/R ratio ≥0.25 or Q-wave duration ≥40 ms in two or more contiguous leads 5
• ECG criteria for anterior MI in the setting of PRWP have 85% sensitivity and 71% specificity when considering patient sex, ST-T wave changes, S wave amplitude in V2-V3, and sum of R wave amplitude in V3-V4 5, 7
• If pathological Q waves are present with PRWP, immediately obtain echocardiography to assess wall motion abnormalities and left ventricular function 5

2. Left Ventricular Hypertrophy

• LVH causes PRWP through increased posterior forces that diminish anterior R-wave amplitude 1, 5
• Look for increased QRS voltage in lateral leads (I, aVL, V5, V6) and associated ST-segment depression with T-wave inversion (secondary repolarization abnormalities) 6, 5
• QRS voltages decline with age and are influenced by gender, race, and body habitus 6
• In athletes, voltage criteria for LVH represent physiologic adaptation and do not require further evaluation when isolated 1
• When LVH is suspected, obtain echocardiography to quantify left ventricular mass and assess diastolic function 5

3. Right Ventricular Hypertrophy

• RVH produces PRWP by shifting the QRS vector rightward and anteriorly 1, 5
• Associated findings include right axis deviation (>90°) and tall R waves in V1 6, 5
• Up to 13% of athletes fulfill Sokolow-Lyon criteria for RVH as normal physiologic adaptation 1
• If RVH is suspected, obtain echocardiography to assess right ventricular size, function, and estimated pulmonary artery pressure 5

4. Normal Variant

• PRWP occurs in 8% of individuals with completely normal cardiac evaluation 8
• This variant is associated with a low cardiothoracic ratio (mean 0.425 vs. 0.445 in controls), particularly in males 3
• The positive predictive value of PRWP for coronary artery disease in the general population is only 7.3% 3, 1
• Normal variant is diagnosed by exclusion: no pathological Q waves, no other ECG abnormalities, and no cardiac symptoms or risk factors 5

Risk Stratification Algorithm

High-Risk Features Requiring Immediate Cardiac Evaluation: 1, 5

• Symptoms of chest pain, dyspnea, or syncope
• Pathological Q waves present
• ST-segment depression or T-wave abnormalities in precordial leads
• Reversed R wave progression (RRWP)
• Multiple cardiovascular risk factors (diabetes, hypertension, smoking, hyperlipidemia)

Intermediate-Risk Features Requiring Selective Evaluation: 1, 9

• Age >50 years with isolated PRWP
• Chronic alcohol use (associated with cardiomyopathy)
• Signs of chronic lung disease with cor pulmonale

Low-Risk Features (May Not Require Further Testing): 1, 3

• Young, asymptomatic patients without family history of sudden cardiac death
• Isolated PRWP without other ECG abnormalities
• No cardiovascular risk factors

Prognostic Implications

• Major ECG abnormalities including pathological Q waves and ST-segment depression predict all-cause mortality (HR 1.8), cardiovascular mortality (HR 3.3), and CHD mortality (HR 2.3) 6, 1
• RRWP is rare (0.3% prevalence) but highly specific: 76% have cardiac pathology, with 41% having prior anterior MI and 17% having ischemic heart disease without MI 4
• All patients with RRWP and ischemic heart disease had left anterior descending artery stenosis 4

Common Pitfalls to Avoid

• Never dismiss RRWP as benign—it has 76% association with cardiac pathology 5, 4
• Do not rely on PRWP alone to diagnose anterior MI—sensitivity is only 85% even with comprehensive criteria 5, 7
• Always compare with prior ECGs if available to assess for interval changes 9
• In patients with low diaphragm position (obstructive pulmonary disease), V3 and V4 may be located above ventricular boundaries and record negative deflections simulating anterior infarction 6, 1
• In women with large breasts, electrode placement beneath versus on top of the breast can affect voltage measurements 6