EKG Changes in Pulmonary Embolism

Most Common EKG Findings

Sinus tachycardia is the single most frequent abnormality, present in approximately 40% of PE cases, but it is entirely non-specific 1, 2, 3
In milder cases of PE, sinus tachycardia may be the only detectable abnormality 1, 2, 3
T wave inversions in the right precordial leads (V1-V4) are the most clinically significant finding, as they indicate RV strain and are typically found in more severe cases 1, 2, 3
QR pattern in lead V1 suggests acute RV overload but is uncommon 1, 2, 3
Right bundle branch block (complete or incomplete) occurs in 4.8-9% of PE cases and is associated with RV strain 1, 2, 3
Atrial fibrillation and other atrial dysrhythmias occur in 10-23.5% of PE patients 1, 2, 3

The primary role of EKG is to exclude alternative diagnoses such as acute myocardial infarction, pericarditis, and other cardiac conditions that may present similarly 4, 5
EKG should be obtained immediately in suspected PE to rule out acute MI and pericardial disease 4
EKG must be used in conjunction with clinical prediction scores (Wells or revised Geneva) rather than in isolation 1, 2, 3, 4
EKG findings correlate with severity of pulmonary hypertension and RV dysfunction 4
The presence of ≥1 classic RV strain sign is associated with higher adverse event rates 4
In patients with hemodynamic instability, EKG may show ischemic patterns combined with RV strain, prompting urgent echocardiography 5

First, use the EKG to exclude acute MI, pericarditis, and other cardiac emergencies 4, 5
Look specifically for RV strain pattern (T wave inversions in V1-V4), as this has the highest specificity (97.4%) and suggests more severe PE 1, 2, 3
Integrate EKG findings with clinical prediction scores (Wells or revised Geneva) to determine pre-test probability 1, 2, 3, 4
If hemodynamic instability is present with RV strain on EKG, obtain urgent echocardiography to assess RV function 5
Implement continuous EKG monitoring during transport/transfer for suspected PE, as arrhythmias may develop 4

The European Society of Cardiology guidelines note that ECG signs of RV strain are "generally associated with the more severe forms of PE" 6, 7, 8
Sinus tachycardia is the most common finding at 26-40%, but is entirely non-specific 8

Individual ECG signs and symptoms are neither sensitive nor specific for PE 6, 7
When RV strain patterns are present on ECG, they indicate more severe PE with greater hemodynamic compromise 6, 7, 8

Echocardiographic RV dysfunction is found in at least 25% of PE patients, which is substantially higher than the 11-17% showing ECG strain patterns 9, 10, 11
This discrepancy indicates that ECG is insensitive for detecting RV dysfunction compared to imaging modalities 9, 10, 11