Coronary artery aneurysm

Overview

Coronary artery aneurysms (CAA), also referred to as ectasias, are typically defined as a dilatation in the diameter of a coronary artery segment to more than 1.5-fold normal size. Coronary artery aneurysm is an uncommon condition that may commonly represent the result of vasculitis, excess active transforming growth factor β (TGF-β) or dysregulation of matrix metal loproteinases. When encountered at autopsy, coronary artery aneurysm may represent the intermediate cause of death because abnormal blood flow within the aneurysm may lead to thrombus format ion, occlusion, embolization, myocardial ischemia, or myocardial infarct ion. Coronary artery aneurysm is a neglected topic in the pathology literature, with contributions limited primarily to reports of single cases.

Symptoms

Abnormal dilation or swelling of a heart artery. The dilated portion is weakened and can burst.Signs and symptoms are due to ischemia secondary to arterial stenosis or occlusion; aneurysms and ectatic collateral vessels are not uncommon features and most of the time develop as a compensatory mechanism. Imaging findings in early phases are consistent with arterial wall enhancement and thickening, while in later phases, imaging features are dominated by stenosis and aneurysms or ectasia.

Causes

Inflammation spilling over into the tunica media from the tunica intima may link atherosclerosis to aneurysm formation, but vasculitis without atherosclerosis causes coronary artery aneurysms in young children with Kawasaki disease. Increased proteolysis of extracellular matrix proteins is probably one mechanism of coronary artery aneurysm formation, either due to overactive matrix metalloproteinases or underactive inhibition of these proteinases, and an excess of transforming growth factor may be another mechanism in the pathogenesis. Coronary atherosclerosis is a universal disease of adults, but only 1.5% of them have coronary aneurysms; this small group may be those with a second coronary artery disease, such as vasculitis.

Source:

Larry Nichols, et al. Coronary Artery Aneurysm - A Review and Hypothesis Regarding Etiology Arch Pathol Lab Med. 2008;132:823–828

Diagnosis

Most of the patients remain asymptomatic, and aneurysms are incidentally found during diagnostic coronary angiography or at necropsy.With the increase in angiography and the more widespread use of high resolution CT scans and MRI imaging, the diagnosis of coronary aneurysms is likely to become more frequent, and the need for evidence-based management strategies will grow. 

Prognosis

Coronary artery dilatation is an uncommon finding; however, with the advent of new noninvasive methods for the evaluation of the coronary arteries, dilatation is more frequently found. Most of the patients are asymptomatic, and dilatation is an incidental finding.

Treatment

Although several groups of investigators have reported data on coronary artery aneurysms, there are no controlled clinical studies to evaluate optimal therapy for coronary artery aneurysms because of the rarity of this condition. Medical management depends on the presence or absence of coexisting obstructive coronary artery disease rather than the sole presence of coronary ectasia or aneurysm. In patients with coronary artery disease, treatment is guided by the underlying coronary artery stenosis. In the absence of obstructive coronary artery disease, treatment is not well established because it is based mainly on case reports and continues to be a therapeutic dilemma. Conservative measures consist of attempts to prevent thromboembolic complications with anticoagulant therapy and administration of antiplatelet drugs.

Surgery may be considered as a means to avoid complications, and surgery is indicated in patients with obstructive coronary artery disease or evidence of embolization leading to myocardial ischemia and in those patients with evidence of enlargement of saccular coronary artery aneurysms with increased risk of rupture. Percutaneous treatment with noncovered or coated stents is another option in patients with a fistula that needs closure. As previously mentioned, in Kawasaki disease, the use of high-dose intravenous therapy with γ-globulin, together with aspirin, reduces the rate of occurrence of coronary lesions.

Source:

Mariana Díaz-Zamudio, et al. Coronary Artery Aneurysms and Ectasia: Role of Coronary CT Angiography. RadioGraphics, 29, 1939-1954.