Myocardial Infarction (MI) Complications

Special Situations – CAD - STEMI

Aortic Dissection

An ascending aortic dissection that occludes the right coronary ostium may result in an inferior STEMI. This is relatively uncommon but must be recognized quickly, as surgical intervention is crucial.

No-reflow

When coronary intervention is performed for STEMI, there is a risk of “no-reflow” or “microvascular obstruction.” Despite conduit vessel patency, myocardial perfusion may be reduced due to multiple mechanisms including ischemia, reperfusion, endothelial dysfunction, distal thromboembolism and microvascular arteriolar spasm.

There are both patient-related and lesion-related risk factors for no-reflow. The patient-related factors include delayed presentation to the catheterization laboratory, hyperglycemia and hypercholesterolemia. Lesion-related factors include the composition of the plaque and the amount of intravascular thrombus present. (Rezkalla 2017;2a-b)

Management of no-reflow events is controversial and beyond the scope of this section.

Pregnancy

ST segment elevation MI is rare during pregnancy but does occur. Atherosclerotic plaque rupture in women with typical risk factors is the most common etiology. The risk of spontaneous coronary artery dissection risk also increases during pregnancy. PCI is the primary treatment option; thrombolytics and glycoprotein IIb/IIIa inhibitors are contraindicated during pregnancy.

STEMI Mimics

Many disorders can mimic STEMI in both the symptomatic presentation and the ECG findings, as previously discussed. STEMI is an ACS, involving an unstable atherosclerotic plaque and thrombosis. Other disorders may cause chest pain symptoms and ischemic ST segment elevation on the ECG, but are not caused by atherosclerotic plaque rupture. These include coronary spasm, cocaine abuse, aortic dissection, coronary vasculitis, Takotsubo cardiomyopathy (stress-induced cardiomyopathy), emboli to the coronaries, myocarditis, trauma or cardiac contusion and congenital coronary anomalies.

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