Utility of ST segment depression in lead AVL in the diagnosis of right ventricular infarction.

We performed twelve lead electrocardiograms(ECG) and right precordial leads on twenty-two consecutive patients with first inferior wall acute myocardial infarction (MI) diagnosed by classical Q waves and elevation of cardiac enzymes. The presence of right ventricular MI was established by either technetium 99 (TC-99) pyrophosphate scanning or 2-dimensional (2-D) echocardiography by observers unrelated to the study and not aware of the electrocardiographic findings. In patients with established right ventricular MI (n = 15/22), ST segment elevation > or = 0.1 mV in lead V4R placed in the right precordial lead position had 91% (10/11) sensitivity in diagnosing right ventricular MI. ST segment depression in lead AVL > or = 0.1 mV had 100% sensitivity in diagnosing right ventricular MI (15/15). In the seven patients without right ventricular infarction, the absence of ST segment elevation in lead V4R had 100% specificity (7/7), while the absence of ST segment depression in lead AVL had 57% specificity (4/7) in excluding right ventricular infarction. The data indicate that in the presence of inferior wall MI, ST segment depression in lead AVL is a sensitive, but not very specific sign of right ventricular MI. Therefore, its presence in patients with inferior wall MI should lead to further investigations to diagnose or exclude right ventricular MI.