Coronary artery ectasia (CAE) is a dilation of the coronary artery lumen. The term "ectasia" refers to diffuse dilation of a coronary artery, while focal coronary dilation is called a "coronary aneurysm." The definition of coronary artery ectasia is a dilatation exceeding more than one-third of the coronary artery length with the diameter of the dilated segment measuring more than 1.5 times the diameter of a normal adjacent segment. Coronary artery ectasia is well recognized, but uncommon findings encountered during diagnostic coronary angiography. The classification of coronary artery ectasia subdivides into four groups:
The etiology of coronary artery ectasia can be enigmatic. Atherosclerosis lays claim to the principal etiologic cause responsible for greater than 50% of cases in adults, while Kawasaki disease is the most common cause in children and young adults. The histology of atherosclerosis and ectasia are comparable.
Rarely coronary artery ectasia can be genetic. Acquired etiologies include atherosclerosis, Kawasaki disease, mycotic or septic emboli, Marfan syndrome, arteritis from polyarteritis nodosa, Takayasu disease, or systemic lupus erythematosus. Coronary artery ectasia secondary to iatrogenic causes includes secondary to percutaneous transluminal coronary angioplasty (PTCA), stents, directional coronary atherectomy.
Some of the risk factors for coronary ectasia include:
The incidence varies between 0.3% and 4.9%. The CASS registry found coronary artery ectasia in 4.9% of coronary angiograms. Coronary artery ectasia classifies as small (vessel size under 5 mm), medium (vessels size 5 to 8 mm), and giant (vessel size over 8 mm). Based on location most common location is in the right coronary artery (68%), proximal left anterior descending (60%), and left circumflex (50%).
Based on shape, coronary artery ectasia can be divided into "saccular," when the transverse diameter is larger than the longitudinal diameter or "fusiform" when the longitudinal diameter is larger than the transverse diameter.
The exact pathophysiology of coronary artery ectasia is unknown. CAE is an anatomical variant or a clinical constellation of coronary artery disease because it may present with myocardial ischemia or coronary syndrome. The mechanism of luminal dilation in some atherosclerotic vessels is ambiguous; atherosclerosis typically causes narrowing of the vessel lumen. Due to the arterial remodeling, there is an expansion of the medial and external elastic membrane of the blood vessel. This proposed methodology of arterial remodeling may be operative in the case of coronary artery ectasia. Intravascular ultrasound reveals that arterial remodeling can be bidirectional depending upon expansion or contraction of the external elastic membrane. Coronary artery ectasia is believed to be exaggerated expansive remodeling of the external elastic membrane resulting in luminal expansion.
Enzymatic degradation of the extracellular matrix by matrix metalloproteinases (MMP) and other lytic enzymes and thinning of the tunica media associated with severe chronic inflammation is considered the principal pathogenesis of the expansive remodeling. CAE is also related to apical hypertrophic cardiomyopathy with high wall tension. In addition to that, iatrogenic mechanisms, e.g., percutaneous coronary interventions, including balloon angioplasty, stent placement, and atherectomy, can lead to the formation of aneurysms or ectasias. The mechanism is felt to be the injury of the media of the blood vessel.
Histology usually shows it thickened fibrotic intima with lipid deposition. The internal elastic laminal layer usually suffers disruption leading to the reduction in medial elastic tissue. This loss of elastic tissue is the primary cause along with chronic vascular inflammation leading to ectasia.
The symptoms of coronary artery ectasia may be associated with concomitant coronary disease, Kawasaki disease, or connective tissue disease. Most patients are asymptomatic. Patients with CAE may present with angina post-stress tests and acute coronary syndrome. Diminished coronary flow speed or stagnancy of blood flow may cause exercise-induced angina without coexistent stenotic coronary artery disease. Formation of intracoronary thrombus or dissipation leading to distal emboli may be the trigger of acute coronary syndrome, which is hastened by stagnant flow in the ecstatic coronary segment. The hypothesis is that coronary artery ectasia is predisposed to vasospasm, which may elicit angina or acute coronary syndrome. In people less than 50 years old, CAE should raise concern for connective tissue disorders and vasculitides.
Coronary angiography is the gold standard in diagnosing coronary artery ectasia. Intravascular ultrasound (IVUS) is critical to the evaluation of luminal characteristics and pathologies. Distortions in flow and washout are common in CAE and are related to the severity of ectasia. Signs of stagnant flow include delayed antegrade contrast filling, segmental backflow, and stasis in the ectatic coronary segment.
Other investigative techniques include MRA and coronary CTA. For the follow up of patients, MRA is the preferred modality.
Management of coronary artery ectasia is fraught with uncertainty because the rarity of CAE prevents large randomized trials comparing different treatment approaches. When CAD coexists, intense primary and secondary risk factor modifications are mandatory. Management of isolated coronary artery ectasia in a case with angina or myocardial ischemia includes ASA, statin, and anti-ischemic medications. Acute coronary syndromes associated with CAE may require thrombolysis, heparin administration, and glycoprotein IIb/IIIa receptor inhibitors. Thrombus aspiration may be necessary during primary PCI. Percutaneous and surgical interventions are often necessary for patients with CAE and stenotic lesions where angina persists despite maximal medical therapy. Optimal stent sizing is essential to prevent misplacement, and embolization of stents. Many authors recommend chronic anticoagulation; however, no randomized trial demonstrates its benefit in CAE. The anticipated benefit must counterbalance against the risk of hemorrhage.
Surgery is rarely done but is sometimes a necessity in patients who have recurring complications. The surgery involves ligation of the proximal and distal segment of the ectatic vessel and replacing it with a bypass graft. There should be no attempt to repair the ectatic vessel as the results are poor.
The prognosis for coronary artery ectasia is directly related to the severity of concomitant coronary artery disease. Coronary artery ectasia with underlying coronary artery disease is a dangerous combination with an increased potential for adverse cardiac events. Isolated CAE still carries the risk of myocardial ischemia and infarction. Type 1 and Type CAE carry a higher risk than Type 3 and type 4 CAE. No reported data shows a relationship between the diameter of an artery and the outcome.
In complicated cases involving multiple coronary arteries or left main disease; an interprofessional team approach is preferred that includes interventional cardiologist, cardiac surgeon, cardiac intensivist, and ICU and cardiovascular specialty trained nurses, radiologist, and cardiac pharmacists to devise a treatment plan to reduced complications and improve outcomes. The cardiology nurse and the pharmacist often provide education. [Level V]
The overall management is similar to a patient with coronary artery disease. However, because of a lack of long term studies, the ideal management of this disorder remains unknown.
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