Overview of coronary artery ectasia (CAE)
Coronary artery ectasia (CAE) is a rare anomaly of the coronary arteries in which the limited or diffuse dilatation of the coronary arteries exceeds the diameter of the adjacent normal coronary arteries by 1.5 times or more for a variety of reasons. It often involves multiple blood vessels and is more common in right coronary artery dilatation. It is a rare coronary artery anomaly and is more common in males than females. Clinically, a limited dilatation with a diameter more than twice the diameter of the adjacent normal segment is also known as a coronary artery aneurysm (CAA).
Etiology
Etiology includes congenital and acquired. The former is rare and often occurs in association with other structural heart diseases, such as aortic valve leaflet deformity and ventricular septal defects. The latter include atherosclerosis, Kawasaki disease, infectious septic thromboembolism (e.g., mycobacteria, syphilis, Lyme spirochetes, etc.), connective tissue disease, Marfon syndrome, aortitis, and medical sources such as percutaneous transluminal coronary angioplasty and stenting. Of these, Kawasaki disease is the leading cause of morbidity in children and adolescents, and atherosclerosis is the leading cause of morbidity in adults. Risk factors include male gender, smoking, hypertension, and cocaine use.
The pathogenesis of coronary artery dilatation disease is unclear, and the degradation and loss of elastic fibers in the middle layer of the coronary artery is thought to be central to the pathogenesis. A variety of factors, such as hyperhomocysteinemia, hyperinsulinemia, Mycoplasma pneumoniae infection, and nitric oxide over-exposure, lead to enhanced activity of extracellular matrix metalloproteinases and intracellular cysteine proteases and serine proteases, causing the middle layer of the coronary artery and the inner and outer elastic membrane degradation, causing inflammatory cells to diffuse into the middle layer of the blood vessels, promoting the proliferation and migration of local vascular smooth muscle cells and the production of extracellular matrix, and ultimately causing dilatational remodeling of the coronary arteries. In addition, risk factors associated with atherosclerosis, such as deposition of lipoproteins in the vessel wall, hyperactivation of the RAAS system and excessive oxidative stress, are also involved in vascular remodeling. Genetic factors play a role, with a high prevalence of familial hypercholesterolemia. Platelet activation and vasodilation cause blood turbulence and retention, increasing the risk of platelet aggregation and thrombosis.
Symptoms
Usually asymptomatic, only incidentally detected on cardiac examination. Stable angina is the most common symptom, and malignant arrhythmias and even sudden death can also occur when spontaneous clips form. Rarely, aneurysm rupture occurs, causing acute cardiac tamponade with life-threatening symptoms such as sudden chest tightness, dyspnea, pallor or cyanosis.
Examination
1. Coronary angiography
Coronary angiography is the gold standard for the diagnosis of this disease, which can simultaneously understand the degree of coronary artery dilatation, abnormal blood flow, the location and number of lesions, and whether it is combined with coronary atherosclerosis, etc., and it can also provide the basis for interventional or surgical treatment. Typical imaging manifestations include coronary artery dilatation, slowing of blood flow, delayed perfusion of contrast medium, local regurgitation phenomenon and retention of contrast medium in the lesion site.
2.Coronary magnetic resonance imaging
Coronary magnetic resonance imaging has the advantages of accuracy, non-invasiveness, non-radiation, etc. It has the same diagnostic value as coronary angiography and can provide more measurement data to assist in analyzing the risk of thromboembolic events, and is often used for post-treatment follow-up.
3. Coronary CT angiography
Coronary artery CT angiography (CTA) can clearly show the shape and structure of coronary artery dilatation, such as segmental or total dilatation, or cystic, fusiform, aneurysmal, bead-like. In the case of verrucous lesions, the bulbous nodules and the corresponding coronary arteries show wide-base changes. Coronary CT angiography is a non-invasive diagnostic method with low radiation dose and can be used for patient follow-up.
4. Intravascular ultrasound
Intravascular ultrasound can measure the size of vascular lumen and analyze the wall composition to identify true aneurysm and pseudoaneurysm, which has important clinical application value. Intravascular ultrasound is valuable in the diagnosis and follow-up of coronary artery dilatation caused by juvenile Kawasaki disease.
Diagnosis
The gold standard for diagnosis is coronary angiography. Coronary artery dilatation is diagnosed when the dilatation of the diseased coronary artery exceeds 1.5 times or more the diameter of the adjacent normal coronary artery. Dilated coronary arteries are categorized as small (<5 mm), medium (5-8 mm), and large (>8 mm) according to the size of the dilated coronary artery. The shape of the lumen is categorized into cystic dilatation (transverse diameter > longitudinal diameter) and systolic dilatation (transverse diameter < longitudinal diameter).
Treatment
Complex etiology and mechanisms need to be considered, and there is no optimal treatment due to the low prevalence. Available treatments include pharmacologic, surgical, and interventional therapies.
1. Pharmacologic treatment
There is no consensus recommendation. Due to excessive platelet activation and most combined coronary artery disease, all patients are recommended to take antiplatelet drugs, such as aspirin; when there is localized turbulence and stagnation of blood flow in the diseased coronary artery, long-term oral warfarin is recommended; dual antiplatelet therapy has the possibility of increasing the risk of bleeding, and should be weighed against the advantages and disadvantages of using it with caution. Diltiazem prevents vasospasm; vasoconverting enzyme inhibitors (ACEIs) and statins may delay vascular remodeling and slow the disease process; statins inhibit matrix metalloproteinase production and activity, regulate lipids, and may be beneficial. Nitrates may increase epicardial vasodilatation and induce or aggravate angina, and should be avoided.
2.Surgical treatment
Surgical treatment is preferred for patients with left main artery aneurysm, aneurysm diameter >10 mm or aneurysm up to 3-4 times of the originating vessel. According to the size of the aneurysm, the distribution of side branches and the degree of stenosis, coronary artery bypass surgery can be used to simultaneously ligate or excise the aneurysm. If life-threatening acute events occur, emergency surgical management is considered. Surgical removal of thrombus can also be considered when the huge tumor is combined with thrombosis.
3. Intervention
(1) Implantation of stents in dilated CAA tumors can reduce or even disappear the tumor and reduce cardiovascular events.
(2) In the case of cystic or concomitant coronary artery fistula, interventional therapy can be used for occlusion.
Prognosis
The prognosis is relatively good and most are not life-threatening. When combined with the presence of coronary obstructive lesions, the prognosis can be affected by the severity of the obstruction, and myocardial ischemia and therapeutic effects need to be evaluated and targeted treatment.