ECG Signs of Pulmonary Embolism

Most Common ECG Findings

Sinus tachycardia is the most frequent finding, present in the majority of PE cases, though it lacks specificity 1
Non-specific ST-segment and T-wave changes occur frequently but are of limited diagnostic value alone 1
Right bundle branch block (complete or incomplete) may be present, particularly in more severe cases 1
Features of acute right heart strain including right axis deviation and right bundle branch block are more common with massive emboli 1

The American Thoracic Society recommends that ECG findings have minimal standalone diagnostic accuracy and should never be used in isolation to rule in or rule out PE, with an overall predictive value of any single ECG feature being less than 80% 1
The European Society of Cardiology suggests that the primary role of ECG is to exclude alternative diagnoses such as acute myocardial infarction, pericarditis, left heart failure, and other cardiac conditions that may present similarly 2, 1
The European Society of Cardiology also recommends that ECG can support clinical suspicion when combined with other clinical features, but cannot confirm or exclude PE 1
Identify patients at higher risk when signs of right ventricular strain are present, though echocardiography is superior for this purpose, according to the European Heart Journal 3

The European Heart Journal recommends that in suspected high-risk PE with hemodynamic instability, the ECG may show ischemic patterns combined with right ventricular strain, prompting urgent echocardiography to assess for RV dysfunction 4