Young age (<35 years) and lack of coronary risk factors raise the suspicion of congenital coronary anomalies or congenital coronary aneurysm. A careful history to exclude cocaine use (supported by tox screen if needed) is mandatory in STEMI patients without significant atherosclerotic risk factors, as is rheumatic history.
Coronary spasm has also been described with patients receiving chemotherapeutic drugs such as 5-fluorouracil, and those talking herbal medicines. A careful medical reconciliation should be performed on all chest pain patients and review of “vasospastic potential” performed, and this includes use of estrogen replacement therapy (coronary dissection).
Hypercoagulable/malignancy history should be reviewed, and subtherapeutic INR for patients on Coumadin should be assessed for the possibility of coronary embolism.
Presentation/Findings
Congenital Coronary Anomalies
Present in 1–2% of the general population but 4% of autopsies for MI. When coronary arteries arise from the contralateral sinus of Valsalva, the anomalous artery may course between the great vessels. States of increased cardiac output may cause either compression or torsion of the proximal coronary artery resulting in ischemia, infarct, or sudden cardiac death.
Diagnosis is made by imaging based on ACS risk profile of presentation. Cardiac catheterization (high-risk patients) demonstrates interarterial course of anomalous vessel. Direct visualization with cardiac CT or MRI is an advantage when considering these modalities for stress testing in younger populations but must be balanced by cost consideration. Surgical bypass for high-risk anatomy is the preferred treatment.
Myocardial Bridges (“Tunneled” Epicardial Arteries)
Congenital in origin: The course of the epicardial coronary artery dives below the myocardium and is compressed in systole. As the majority of coronary blood flow occurs in diastole, tachycardia with resulting shortened diastolic filling period is often required to produce ischemia. Length of the tunneled arterial segment may not play a significant role in risk.
Diagnosis made by direct visualization by angiography or CT/MRI. The presence of a myocardial bridge does not necessarily imply ischemia is present.
Coronary Aneurysm
Congenital (more common in right coronary artery) or acquired (infection/ inflammation): Turbulent flow in the aneurysm may predispose to thrombus formation and ACS. Acquired aneurysm may be the result of atherosclerosis (50%) or syphilis, mycotic emboli, Kawasaki disease, or lupus. Appropriate serologies should be sent when aneurysm is identified by imaging (see Chapter
2
, Autoimmune Diseases and Chapter
11
, Infectious Diseases).
Embolism
Coronary artery emboli should be considered in any patient presenting with ACS (usually STEMI) in the setting of atrial fibrillation, active infective endocarditis, prosthetic heart valve, known LV thrombus, or left-sided cardiac tumor (right-sided tumors require a right-to-left shunt to be present). Initial triage is performed as dictated by ACS algorithm, and diagnosis often made angiographically. Coronary embolism most often involves the LAD and may resolve spontaneously with anticoagulation.
Embolism or spasm should be considered for angiographically normal arteries in the setting of MI.
