What is the most common electrocardiogram pattern associated with pulmonary hypertension?

Most Common ECG Pattern of Pulmonary Hypertension

Right ventricular hypertrophy and right axis deviation are the most common ECG patterns in pulmonary hypertension, occurring in 87% and 79% of patients respectively. 1

Primary ECG Findings in Pulmonary Hypertension

The electrocardiogram reflects the right heart remodeling that occurs with elevated pulmonary pressures, though it lacks sufficient sensitivity to serve as a screening tool alone. 1

Most Prevalent Patterns

Right ventricular hypertrophy (RVH) and right axis deviation dominate the ECG presentation:

• Right axis deviation (≥100°) occurs in 79% of patients with idiopathic pulmonary arterial hypertension, making it one of the most common findings 1
• Right ventricular hypertrophy is present in 87% of patients with IPAH 1
• Right axis deviation should be required for diagnosis of RVH in nearly all cases 1, 2

Specific ECG Criteria Suggestive of Pulmonary Hypertension

The following patterns indicate right heart strain: 1

• Tall R wave with small S wave and R/S ratio ≥1 in lead V1 - this reflects the anterior forces of the hypertrophied right ventricle 1
• qR complex in V1 - highly specific for RVH 1
• rSR' pattern in V1 - suggests volume overload pattern similar to incomplete right bundle branch block 1
• Large S wave with small R wave and R/S ratio <1 in leads V5 or V6 - reflects the rightward shift of electrical forces 1
• S1S2S3 pattern - persistent S waves across all leads 1

Right Atrial Enlargement

P-wave abnormalities indicating right atrial enlargement are common:

• Tall P wave (≥2.5 mm) in leads II, III, and aVF with frontal P-axis ≥75° 1
• P-wave amplitude in lead II ≥0.25 mV carries prognostic significance, associated with 2.8-fold greater risk of death over 6 years 1, 3
• Right atrial enlargement occurs in 36.9% of PH patients 4

Repolarization Abnormalities

ST-T segment changes are frequently present:

• ST segment depression and T wave inversion in right precordial leads (V1-V3) 1, 5
• These "secondary ST-T abnormalities" also occur in leads II, III, and aVF 1, 5
• These changes reflect the strain pattern of pressure overload 1, 2

Diagnostic Performance and Clinical Context

Sensitivity and Specificity Limitations

The ECG has important limitations for detecting pulmonary hypertension:

• Sensitivity of right axis deviation is only 73% and specificity is 70% in patients with mean pulmonary artery pressure of 50 mmHg 1
• Sensitivity of RVH criteria is only 55% with similar specificity of 70% 1
• 8 of 61 patients (13%) with severe PAH had completely normal ECGs despite mean PAP of 50 mmHg 1
• No patient with established PH had a completely normal ECG in one African cohort, though this may reflect more advanced disease at presentation 4

Highest Predictive Value Patterns

Certain ECG combinations have excellent positive predictive values (>80%): 6

• QRS axis >110° combined with R/S ratio in V1 ≥1 or R in V1 >7 mm has 100% positive predictive value 6
• R/S ratio in V1 >1 alone has >80% positive predictive value 6
• Right axis deviation with QRS axis ≥110° has the best positive predictive value for severe PH (PASP ≥60 mmHg) 6

Accuracy Varies by Underlying Etiology

The diagnostic accuracy of ECG for RVH differs substantially by disease context: 1, 7

• Highest accuracy in congenital heart disease 1, 7
• Intermediate accuracy in acquired heart disease and primary pulmonary hypertension 1, 7
• Lowest accuracy in chronic obstructive pulmonary disease 1, 7

Special Considerations in COPD

Chronic obstructive pulmonary disease creates a distinct ECG pattern that can mask or mimic RVH:

• Low voltage in limb leads due to hyperinflation and low diaphragm position 1, 2
• Rightward, superior, or indeterminate frontal plane QRS axis 1, 2
• Rightward P-wave axis (>60°) 1, 2
• Persistent S waves in all precordial leads 1, 2
• Low R-wave amplitude in V6 1, 2
• RVH should only be diagnosed in COPD if R-wave amplitude in V1 is relatively increased 1, 2, 3

Pressure vs. Volume Overload Patterns

Two distinct ECG patterns reflect different hemodynamic states:

Pressure Overload Pattern

• Predominantly tall R waves in right precordial leads (Rs, R, or Qr complexes) 1, 2, 7
• Right axis deviation 1, 2, 7
• ST depression and T-wave inversion in right precordial leads 1, 2, 7

Volume Overload Pattern

• Similar to incomplete right bundle branch block (rSR' pattern) 1, 2, 7
• Right axis deviation 1, 2, 7
• Secondary ST-T abnormalities 1, 2, 7

Prognostic Implications

Certain ECG findings predict worse outcomes:

• P-wave amplitude in lead II ≥0.25 mV: 2.8-fold increased risk of death 1, 3
• Each additional 1 mm of P-wave amplitude in lead III: 4.5-fold increased risk of death 1
• Presence of composite right heart disease pattern on ECG (RVH, right axis deviation, right atrial enlargement, or RBBB) associated with increased risk of clinical worsening (HR 1.42) 8

Critical Clinical Pitfalls

Important caveats when interpreting ECG in suspected pulmonary hypertension:

• A normal ECG cannot rule out pulmonary hypertension - up to 13% of patients with severe PH may have normal ECGs 1, 4, 6
• ECG abnormalities are more likely in severe rather than mild PH, explaining discordance with normal echocardiography in early disease 3
• Right axis deviation can precede echocardiographic detection of pulmonary hypertension 3
• Do not rely solely on echocardiography to exclude PH when ECG shows right heart strain - echo can underestimate PA pressures, particularly in early disease 3
• Many ECG findings can occur as normal variants, requiring clinical context for proper interpretation 1, 7
• No single ECG criterion should be used exclusively; multiple criteria improve diagnostic accuracy 1, 7, 3

Practical Diagnostic Approach

When evaluating ECG for pulmonary hypertension:

• Look first for right axis deviation and RVH as these are the most common findings 1
• Assess for tall R waves in V1 and deep S waves in V5-V6 as these have high positive predictive value 6
• Check for P-wave abnormalities indicating right atrial enlargement, which carry prognostic significance 1
• Consider the clinical context - symptoms of dyspnea, reduced exercise tolerance, connective tissue disease, or risk factors for PH 3
• If clinical suspicion exists despite normal or equivocal ECG, proceed with echocardiography and consider right heart catheterization as the gold standard 3
• Adjust interpretation for age, gender, race, and body habitus 1, 7