Final answer:
A true posterior infarct on an EKG can be identified by the presence of specific changes in the ST and T waves, often accompanied by reciprocal changes in the anterior leads.
Step-by-step explanation:
A true posterior infarct on an EKG can be identified by the presence of specific changes in the ST and T waves. In a true posterior infarct, the ST segment is often elevated above the baseline in the leads V1-V3, while the T waves may be inverted in these leads. These changes are often accompanied by reciprocal changes in the anterior leads, such as ST segment depression and T wave inversion. It is important to note that the diagnosis of a posterior infarct should be confirmed with other diagnostic tools, such as the use of posterior leads or imaging studies.