When Do We Need Additional Chest Leads?

Following a standard (12 lead) ECG, if posterior (V7, V8, V9) or right sided (V4R) infarction is suspected, additional chest leads are required in:

• Patients with inferior ST segment elevation because the majority of right-sided infarcts and posterior infarcts occur as extensions of inferior infarcts. This may affect management – patients with right sided MI and hypotension may respond to fluid resuscitation.
• Patients with anteroseptal ST segment depression (indicating ischaemia) because this may be masking true posterior infarction; this will, if demonstrated, affect immediate treatment.

Standard and posterior ECG lead placement

Figure 1: Standard and posterior ECG lead placement

Click on the links below to see standard-lead and posterior-lead ECG traces.

Standard chest lead

Additional posterior leads

Learning Bite

Be alert to the need for right sided or posterior leads when diagnosing STEMI – they should be performed as routine in all patients with inferior ST elevation or anteroseptal ST depression.