Monday, October 5, 2015

IAM posterior

emDocs - October 1, 2015 - Author: Celedon M - Editors: Singh M and Koyfman A
Isolated or true posterior myocardial infarction (PMI) is a rare entity occurring in about 4% of all ST-elevation myocardial infarctions (STEMIs). The standard ECG lead placement cannot directly illustrate what is occurring in the posterior heart. As a result, it is difficult to diagnose true PMIs. Isolated PMI is an indication for emergent reperfusion therapy and the absence of ST-segment elevation in the standard 12-lead ECG means the diagnosis is often missed. Luckily, most PMIs occur in conjunction with an inferior or lateral STEMI, due to shared blood supply, making them less likely to be missed. Posterior infarction is associated with 15-20% of STEMIs. Isolated PMIs are often misjudged and undertreated as NSTEMIs because the damage is occurring in the ‘blind spot’ of the standard electrocardiogram. The clinical presentation of true posterior MIs are not much different from other myocardial infarctions; however, the lack of ST-elevation on the standard ECG can lead to diagnostic delay. The majority of these patients have a stenosis or occlusion of the right coronary artery (RCA). It is important to recognize acute PMI because patients with inferior or lateral MI who also have PMI have a larger infarct region, lower resultant ejection fraction, as well as higher morbidity and mortality. Additionally, patients with isolated PMI often do not receive reperfusion treatment if a STEMI is not suspected, due to the lack of classical ST-segment elevation."