Coronary ectasia in Takayasu's arteritis

Molecular and cellular insights into the pathogenesis of coronary artery ectasia

Coronary artery ectasia describes a local or diffuse dilatation of the epicardial coronary arteries. This review summarizes the molecular and cellular mechanisms involved in the pathogenesis of coronary artery ectasia. Better identification of the pathophysiologic steps will shed light into the clinical significance and may have direct implications for the management strategies of this disease. Additionally, understanding the underlying etiology may help to improve treatment modalities specific to coronary artery ectasia.

Coronary artery ectasia in atherosclerotic coronary artery disease, inflammatory disorders, and sickle cell disease

Coronary artery ectasia (CAE) or aneurysm is usually defined as dilation ≥1.5-fold the normal vessel diameter. It has an incidence of 1.4-5.3% and is associated with a wide variety of etiologies-mainly congenital, atherosclerotic, and inflammatory ones. CAE is very common in sickle cell disease, and possibly sickle cell trait, with an incidence of 17.7%. It is likely related to the inflammatory process associated with hemoglobin S. Prognosis depends mainly on the underlying etiology. Atherosclerotic CAE does not carry additional risks compared to atherosclerotic coronary artery disease (ACAD) without ectasia. However, isolated CAE in the absence of ACAD carries an increased risk of myocardial infarction (MI) due to vasospasm, slower coronary blood flow, and thrombosis, typically within the dilated segments. Due to lack of studies and guidelines, management recommendations are based on personal experiences. Therapy should be tailored to each individual case after assessment of severity, history of complications, underlying etiology, and comorbidities. Treatment of underlying condition and avoidance of exacerbating factors are essential. Medical therapy in general may include antiplatelets, β-blockers, angiotensin-converting enzyme inhibitors statins, and dihydropyridine calcium channel blockers. In severe CAE or history of MI, the addition of anticoagulation therapy after assessing bleeding risk may be warranted. In acute MI, the large thrombus burden in the dilated segment makes the percutaneous approach very challenging. Aspiration attempts can result in distal thromboembolization. Survival is better in bypass grafting than with medical therapy. Nonetheless, bypass grafting does not improve survival in atherosclerotic CAE. Depending on the physical characteristics of aneurysm, different surgical approaches can be sought; however, the ideal one is unclear.

Novel insights into an old controversy: is coronary artery ectasia a variant of coronary atherosclerosis?

Coronary artery ectasia (CAE) is defined as a localized or diffuse non-obstructive lesion of the epicardial coronary arteries with a luminal dilation exceeding 1.5-fold the diameter of the normal adjacent arterial segment. The incidence of CAE has been reported to range between 2% and 4%, which might be an overestimation of the true frequency. The coincidence of CAE with other systemic vascular dilatations has suggested that the mechanism underlying CAE is not only localized to coronary arteries, but also to other vascular compartments such as aorta or peripheral veins. Although the pathophysiology of CAE remains largely unknown, it was supposed to represent a variant of coronary atherosclerosis. This review focuses on this controversy of whether CAE and coronary artery disease (CAD) are two manifestations of the same underlying process. There are clear differences between CAD and CAE with respect to cardiovascular risk factors such as diabetes mellitus, and pathogenic steps in disease progress such as inflammation or extracellular matrix remodeling. As this review will underscore, the current knowledge of the field is insufficient to finally clarify the causative interrelation between CAE and CAD. The clinical course and treatment of CAE mainly depends on its coexistence with CAD. When coexisting with CAD, the prognosis and treatment of CAE are the same as for CAD alone. In isolated CAE, prognosis is better and anti-platelet drugs are the mainstay of treatment. Surgical treatment can be considered in selected patients. For clarifying the mechanism underlying CAE, additional clinical, histopathological and pathophysiological investigations are required. In fact, every patient with CAE should be evaluated systematically for pathological changes in other vascular territories, both in the arterial system as well as in the venous system, which might occur in the disease process.