ECG Changes Associated with Pulmonary Embolism

Common ECG Findings in Pulmonary Embolism

• The European Society of Cardiology recommends considering ECG changes, including sinus tachycardia, T wave inversions in precordial leads V1-V4, S1Q3T3 pattern, and right ventricular strain pattern, in the diagnosis of pulmonary embolism, though many patients with PE may have normal ECGs 1

Diagnostic Value

• The European Heart Journal states that ECG findings correlate with severity of pulmonary hypertension and right ventricular dysfunction, and should be used as part of a comprehensive assessment including clinical prediction scores 1

Clinical Significance

• The European Heart Journal suggests that ECG should be used in conjunction with clinical prediction scores, such as Wells' rule or revised Geneva score, for diagnosing pulmonary embolism 2, 1
• Continuous ECG monitoring is highly recommended in patients with suspected PE during transport/transfer, as stated by the European Heart Journal 3, 4
• The Thorax journal notes that ECG is also valuable for excluding other diagnoses such as acute myocardial infarction and pericardial disease 5

Electrocardiographic Findings in Pulmonary Thromboembolism

Electrocardiographic Signs

• Inversions of T waves in right precordial leads (V1-V4) suggest right ventricular overload and are more frequent in massive pulmonary thromboembolism 6, 7
• QR pattern in V1 indicates acute right ventricular overload 8
• McConnell sign: hypokinesis of the free wall of the right ventricle with normal or hyperdynamic function of the apex, although not specific to pulmonary thromboembolism 9
• Signo 60/60: coexistence of pulmonary ejection acceleration time <60 ms with a midsystolic "notch" and slightly elevated systolic peak gradient in the tricuspid valve (<60 mmHg) 6, 7

Diagnostic Value of ECG

• The ECG has a sensitivity of 50-60% and a specificity of 80-90% for the diagnosis of pulmonary thromboembolism 10

Clinical Context

• In patients with high-risk suspected pulmonary thromboembolism (with shock or hypotension), the absence of echocardiographic signs of right ventricular overload or dysfunction virtually excludes pulmonary thromboembolism as the cause of hemodynamic instability 6, 7

ECG in Pulmonary Embolism Diagnosis and Management

Introduction to ECG Role

• The European Society of Cardiology recommends that the ECG cannot diagnose or exclude pulmonary embolism but serves primarily to exclude alternative diagnoses and to assess disease severity through detection of right ventricular strain patterns, with a strength of evidence based on expert opinion 11

ECG Findings and Prognosis

• The European Heart Journal notes that ECG abnormalities in PE are typically non-specific, with most changes representing ST segment and/or T wave alterations that can occur in numerous other conditions, with a moderate level of evidence 11, 12
• The presence of right bundle branch block, seen in 4.8-9% of cases, is associated with right ventricular strain and has a moderate level of evidence 13
• Atrial dysrhythmias including atrial fibrillation, occurring in 10-23.5% of patients, are associated with PE and have a moderate level of evidence 13

Clinical Application and Risk Stratification

• The American College of Cardiology recommends obtaining ECG immediately to exclude acute myocardial infarction and pericardial disease as alternative diagnoses, with a high level of evidence 11
• The European Heart Journal suggests using ECG in conjunction with clinical prediction scores rather than in isolation, with a moderate level of evidence 13
• Implementing continuous ECG monitoring during patient transport/transfer for suspected PE is recommended by the European Heart Journal, with a moderate level of evidence 13
• The presence of ≥1 classic RV strain sign is associated with higher adverse event rates, with a moderate level of evidence 12, 13

Diagnostic Integration

• The European Society of Cardiology recommends that the ECG should be viewed as one component of a structured diagnostic approach that includes clinical probability assessment, D-dimer testing, and definitive imaging, with a high level of evidence 11, 13

Electrocardiographic Findings in Pulmonary Embolism

Diagnostic Accuracy and Clinical Utility

• The European Society of Cardiology recommends using the ECG in conjunction with clinical prediction scores, D-dimer, and definitive imaging studies for the diagnosis of pulmonary embolism 14
• The ECG has limited diagnostic accuracy, with a sensitivity of 50-60% and specificity of 80-90%, and a positive predictive value of less than 80% for any individual ECG finding 14
• The use of right-sided ECG derivations can increase the sensitivity of diagnosis, with 88.1% of patients with pulmonary embolism showing at least one abnormality on right-sided ECG 14
• The American College of Cardiology recommends continuous ECG monitoring during transport of patients with suspected pulmonary embolism, especially those with high-risk features and hemodynamic instability 14

ECG Findings in Pulmonary Embolism

Primary Role of ECG

• The European Society of Cardiology recommends that the ECG cannot diagnose or exclude pulmonary embolism but serves to assess disease severity through detection of right ventricular strain patterns, which correlate with pulmonary hypertension severity and RV dysfunction 15

Most Common ECG Abnormalities

• Sinus tachycardia is present in approximately 40% of pulmonary embolism cases, indicating mild disease, according to the European Heart Journal 15
• T-wave inversions in right precordial leads (V1-V4) are the most clinically significant finding with highest specificity (97.4%) for RV strain, suggesting more severe pulmonary embolism, as reported by the European Heart Journal and Annals of Emergency Medicine 15, 16
• The S1Q3T3 pattern is a classic finding present in many pulmonary embolism cases, though sensitivity and specificity are limited, according to Annals of Emergency Medicine 16

Diagnostic Accuracy and Limitations

• The European Heart Journal recommends that the ECG must be used in conjunction with clinical prediction scores, such as the Wells or revised Geneva scores, rather than in isolation, to determine pre-test probability of pulmonary embolism 15
• The Pisa model incorporates ECG findings of acute cor pulmonale with a coefficient of 1.96 and odds ratio of 7.11 for pulmonary embolism diagnosis, as reported by Annals of Emergency Medicine 16, 17

Clinical Algorithm for ECG Interpretation

• The European Heart Journal suggests integrating ECG findings with clinical prediction scores to determine pre-test probability of pulmonary embolism 15
• In cases of hemodynamic instability with RV strain on ECG, urgent echocardiography should be obtained to assess RV function and guide reperfusion therapy decisions, according to the European Heart Journal 15

S1Q3T3 Pattern in Pulmonary Embolism

Diagnostic Accuracy and Limitations

• The American College of Emergency Physicians and European Heart Society suggest that the S1Q3T3 pattern is a classic but insensitive ECG finding in pulmonary embolism, indicating right ventricular strain and correlating with more severe disease, but it has limited standalone diagnostic value and must be integrated with clinical prediction scores and definitive imaging rather than used in isolation 18, 19

Clinical Significance and Prognostic Value

• The American Heart Association recommends that when S1Q3T3 is present, it carries important prognostic implications, indicating acute right ventricular strain and correlating with more severe PE, particularly when part of the broader acute cor pulmonale ECG pattern 18, 19, 20
• The presence of ≥1 classic RV strain sign, including S1Q3T3, is associated with higher adverse event rates and worse short-term prognosis, according to the American College of Cardiology 20
• S1Q3T3 combined with other RV strain patterns correlates with severity of pulmonary hypertension and RV dysfunction, as stated by the European Society of Cardiology 19, 20

Clinical Prediction and Risk Stratification

• The European Society of Cardiology recommends that ECG findings, including S1Q3T3, must be used in conjunction with Wells or revised Geneva scores to determine pre-test probability, never in isolation 19
• The American College of Emergency Physicians suggests that the Pisa model formally incorporates ECG findings of acute cor pulmonale with clinical variables for probability estimation 18

ECG Role in Suspected Pulmonary Embolism

Diagnostic Indications

Integration with Clinical Prediction Scores

Monitoring and Management in Hemodynamically Unstable Patients

Prognostic Correlation