Etiology and prevalence
Coronary artery ectasia (CAE) or aneurismal coronary artery disease (CAD) is dilatation of an arterial segment to a diameter at least 1.5 times that of the adjacent normal coronary artery. (1) CAE can be found in 3%-8% of angiographic and in 0.22%-1.4% of autopsy series. It can be either diffuse, affecting the entire length of a coronary artery, or localised.
It is attributed to atherosclerosis in 50% of cases, whereas 20%-30% are considered to be congenital in origin. In the great majority of these patients, ectasia coexists with CAD. Only 10% -20% of CAE have been described in association with inflammatory or connective tissue disease. (1)
Coronary dilatation is isolated ectasia in association with connective tissue disorders, such as scleroderma, in Ehlers–Danlos syndrome, in different types of ANCA-related vasculitis (2), and also in syphilitic aortitis and Kawasaki disease. (3) In a small percentage of patients, CAE can be congenital in origin.
Acquired CAE should be differentiated from coronary aneurysms following coronary interventions. Occasionally, large ulcerated coronary plaques can be misinterpreted angiographically as coronary aneurysms. Their true cause can be revealed by intravascular ultrasound (IVUS). There is no correlation between ectasy at the coronary artery level and extasy in other arteries of the peripheral vascular system, although they may coexist in some cases.
The presence of aneurysmal segments produces sluggish or turbulent blood flow, with increased incidence of typical exercise-induced angina pectoris and myocardial infarction, regardless of the severity of coexisting stenotic lesions. Patients with pure ectasia (15% of the total population with CAE) have a more benign course, but 39% still present signs of previous myocardial infarction. (1)
All three coronary vessels can be affected by CAE, but almost 75% of patients will have an isolated artery that is ectatic. In patients with concomitant CAD, the proximal and mid-segment of the right coronary artery is the most frequently affected.
In terms of pathophysiology, now it is well known that atheromatous plaques do not project into the lumen, but lie in a depression in the media which may bulge outwards.
This process of 'arterial remodeling is fundamental to the pathophysiology of CAD. The in vivo experience with IVUS has confirmed that both arterial expansion and shrinkage can be a manifestation of coronary atherosclerosis. Positive remodelling (arterial expansion) is frequently associated with unstable coronary syndromes, whereas negative remodelling (arterial shrinkage) is associated with stable coronary syndromes.
- X-ray coronary angiography
X-ray coronary angiography is the main diagnostic technique for the identification of coronary artery ectasia. IVUS is an excellent tool to assess luminal size and characterise arterial wall changes. Angiographic signs of turbulent and stagnant flow include delayed antegrade dye filling, a segmental back flow phenomenon and local deposition of dye in the dilated coronary segment.
- Magnetic resonance angiography (MRA)
The correct follow-up of ectatic vessels is hampered by the need for repeated angiograms. Three-dimensional, non-contrast enhanced, free-breathing coronary magnetic resonance angiography facilitates visualisation of the vast majority of the proximal and middle segments of the coronary arteries. MRA has already been of clinical value for the assessment of anomalous CAD, and it is in some cases superior to X-ray coronary angiography in delineating the course of anomalous vessels, but it is still considered an investigational technique for the assessment of stenotic native vessels.
However, it is proposed as a valuable tool for patients who present with severe left ventricular systolic dysfunction, where the underlying disease is either severe multivessel coronary artery disease or nonischemic cardiomyopathy. We proved that coronary MRA is equal to QCA with the additional advantage of being a non-invasive technique (4, 5), and we also applied MRA alone or in combination with inflammation or viability study in the evaluation of Kawasaki and other autoimmune diseases. (6-8, 2) Compared with computed tomography, magnetic resonance angiography has the advantage of requiring no exposure to radiation or injection of a contrast agent.
- Coronary artery computed tomography (CACT)
Recently, coronary artery computed tomography has been used in the evaluation of ectatic vessels. Coronary artery ectasia usually has been associated with atheromatous changes, but not with significant CAD: thrombosis was a rare complication. Contrast attenuation measurements with CTCA correlate well with the flow alterations assessed with classic X-ray coronary angiography (CCA.) (9) However, CACT cannot be suggested as a technique of choice for patients follow-up due to high radiation doses. Further improvements in terms of radiation doses are expected (with interest) in the near future.
Contrary to atherosclerotic CAD, the medical management of patients with CAE has not been adequately addressed. Previous studies based on the significant flow disturbances within the ectatic segments suggested chronic anticoagulation as a main therapy. However, this treatment has not been prospectively tested and cannot be recommended unless supported by subsequent studies. When coexisting with CAD, the prognosis and treatment of CAE are the same as for CAD alone. In isolated CAE, prognosis is better and antiplatelet drugs are the mainstay of treatment. To improve patients management, it is important to clarify the mechanism underlying CAE.
The coexistence of CAE with obstructive coronary lesions in the great majority of patients and the observed incidence of myocardial infarction - even in patients with isolated coronary ectasias - suggests the generalized administration of aspirin in all patients with CAE. Medications with vasodilating properties against coronary spasm have also been proposed. It is of interest that nitrates, by causing further coronary epicardial dilation, have been shown to exacerbate myocardial ischaemia and are discouraged in patients with isolated CAE.
For patients with coexisting obstructive lesions and symptoms or signs of significant ischaemia despite medical therapy, percutaneous and/or surgical coronary vascularisation can safely and effectively restore normal myocardial perfusion. Coronary artery bypass grafting has been used for the treatment of significant CAD co-existing with ectatic coronary segments. (1)
Figure 1. MR Angiography Indicative of an Ectatic LAD.
Figure 2. MR Angiography Indicative of an Ectatic RCA.