ECG Case 007

Main Abnormalities

• Sinus tachycardia ~ 100 bpm
• Anterior T wave abnormalities: inverted in V1-4
• Inferior T wave abnormalities: inverted in III, aVF
• Subtle ST elevation in III and aVF, without reciprocal changes

Significance of ECG Findings

This pattern of T wave inversions in the right precordial leads V1-4 plus the inferior leads (especially the rightward-facing lead III) is referred to as the right ventricular strain pattern. It is a marker of right ventricular hypertrophy or dilatation.

Diagnosis

In a patient presenting with acute shortness of breath, the combination of…

• Sinus tachycardia
• RV strain pattern in V1-4 (+/- lead III)

… is highly suggestive of acute cor pulmonale due to massive pulmonary embolism.

However, these ECG changes are not specific to PE and may be seen in other conditions associated with pulmonary hypertension and RV enlargement including:

• Chronic lung disease (COPD, lung fibrosis) with chronic cor pulmonale
• Right ventricular hypertropy — e.g. due to congenital causes, valvular heart disease
• Arrhythmogenic right ventricular cardiomyopathy

Anterior T-wave inversion in V1-3 is also seen in Wellens syndrome. The presence of concurrent inferior T-wave inversion, especially in leads facing the right ventricle (III), is highly specific for differentiating pulmonary embolism from Wellens syndrome. For another example of this pattern, see ECG Case 123.

Other ECG findings associated with pulmonary embolism include:

• New right axis deviation
• New right bundle branch block
• New dominant R wave in V1
• Non-specific ST segment changes

The often quoted S_I Q_III T_III  pattern (deep S wave in lead I, Q wave in III, inverted T wave in III) is neither sensitive nor specific for PE and is infrequently seen (20% of cases).

Similarly, sinus tachycardia is not as ubiquitous in PE as people seem to think (< 50% of cases), and certainly should not be relied up to exclude PE.