The standard 12-lead ECG is a less-than-perfect predictor of AMI. The sensitivity of ST-segment elevation for AMI is approx 50% (42), and up to 30% of AMI patients have nonspecific or normal ECGs.
One of the explanations offered for these limitations is that the 12-lead ECG poorly detects posterior wall (43) and right ventricular infarction (RVI) (8). These areas of the myocardium are not directly interrogated by standard leads but are assessed by posterior leads V7, V8, and V9 and right-sided leads V4R, V5R, and V6R (44).
Posterior AMI is one of the most commonly missed ECG findings, and this may be explained by the lack of direct ECG examination (45). In their study, Seyal and Swiryn (46) found that 6% (13 out 250) of infarctions are isolated to the posterior basal surface of the left ventricle.
Posterior and right-sided leads are acquired using the same electrocardiograph as standard leads. For right-sided leads, the lead placement is just the reverse of standard
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