Coronary Artery Calcification

Introduction

Coronary artery calcification is a condition in which calcium deposition occurs in the coronary arteries. It was initially thought to be a benign process, and the calcification increases in accordance with aging. The extent of coronary artery calcification is associated with the degree of atherosclerosis and the rate of cardiac events. This article gives insight into the pathogenesis and management of coronary artery calcification.

What Is Coronary Artery Calcification?

The right and left coronary arteries are the major blood vessels that branch off from the aorta and supply the heart. Coronary artery calcification refers to the buildup of calcium in the coronary arteries. This occurs if plaque (fat and cholesterol) is present in the arteries for many years. Coronary artery calcification denotes the presence of coronary heart disease and is associated with adverse cardiovascular events. Coronary artery calcification is of two types:

• Intimal - Calcification occurs in the intimal or inner layer of the arteries.

• Medial - Calcification occurs in the medial or middle layer of the coronary arteries.

What Is the Difference Between Coronary Artery Calcification and Atherosclerosis?

Atherosclerosis refers to the buildup of fat and cholesterol in and on the walls of the arteries. Plaque formation causes the narrowing of the arteries and obstruction of blood flow. Plaques may rupture and occlude the arteries in the form of clots. Coronary artery calcification occurs many years after plaque formation, and it indicates the worsening of atherosclerosis.

What Are the Risk Factors for Coronary Artery Calcifications?

The prevalence of coronary artery calcification is age-dependent, and it is common in elderly people. Men are more commonly affected by coronary artery calcifications. Dietary calcium intake or calcium supplements do not have any significant association with coronary artery calcification. Medial calcifications are associated with risk factors such as advanced age, chronic kidney disease, hypercalcemia (increased calcium level in the blood), hyperphosphatemia (increased phosphate level in the blood), reduced glomerular filtration rate (decreased efficiency of kidneys), parathyroid hormone abnormalities, diabetes, and duration of dialysis. Risk factors associated with intimal calcifications are advanced age, hypertension, diabetes mellitus, dyslipidemia (imbalance of lipids), smoking, male gender, and renal disease.

How Does Coronary Artery Calcification Occur?

As age advances, calcium from the bloodstream settles in various parts of the body. Damaged or inflamed arteries are common targets for calcium deposition. Calcium deposition in the arteries is similar to bone formation. Calcium deposits start as small deposits and can become larger than three millimeters. Plaque accumulation continues with calcium deposition. Coronary artery calcification causes decreased vascular compliance, abnormal vasomotor responses and impairs myocardial perfusion. Various theories like calcium and phosphate imbalance, the presence of apoptotic bodies, induction of bone formation, circulating nucleation complexes, and loss of inhibitions have been found to be associated with coronary artery calcification.

What Are the Symptoms of Coronary Artery Calcification?

Individuals with coronary artery calcification usually do not present any symptoms. It may cause the following symptoms over a period of time:

• Stable Angina - A chest pain that occurs when the heart muscle needs more oxygen, and it is not getting enough because of heart disease.

• Shortness of breath.

• Heart attack.

What Are the Effects of Coronary Artery Calcification?

Coronary artery calcification causes stiffness in the arteries, and it becomes difficult to expand and contract. This increases the risk of cardiovascular diseases and reduces the blood flow to the heart muscle. Coronary artery calcification can make it hard to perform procedures like percutaneous coronary intervention or angioplasty (a procedure used to widen the obstructed arteries or veins). It causes difficulties in expanding a stent to keep the artery patent.

How Is Coronary Artery Calcification Diagnosed?

Various imaging studies are performed to diagnose coronary artery calcification. It includes the following:

• Chest Radiography - Coronary artery calcification is not visible on a routine chest radiograph. Chest radiographs are not sensitive to detect coronary artery calcification, and they are not recommended for diagnosing coronary artery calcification.

• Computed Tomography (CT) Scan - The electron-beam computed tomography (EBCT) scanner and multi-detector CT scans allow faster acquisition of heart motion to detect calcifications. Coronary artery calcium scoring via CT help in determining the presence o calcifications and their extent. The Agaston score is used to quantify the extent of calcification from the images of the CT.

• Magnetic Resonance Imaging (MRI) - MRI scans are not indicated for diagnosing coronary artery calcifications, as MRI scans cannot detect small quantities of calcification.

• Intravascular Ultrasound - Intravascular ultrasound is a highly sensitive and specific imaging to detect coronary artery calcification. It helps to detect the amount of calcification.

• Optical Coherence Tomography (OCT) - It is a highly sensitive and specific test to diagnose coronary artery calcification. It is used to determine the thickness and volume of calcification as light penetrates calcium.

How Is Coronary Artery Calcification Treated?

There is no proper treatment protocol for coronary artery calcification. Coronary artery calcification is managed with the following procedures:

• Intravascular Lithotripsy - A small cut is made in the patient’s arm or leg, and a catheter is inserted to reach the heart. The lithotripsy emitters emit pressure waves at the end of the catheter. This breaks the calcification and relieves the restriction in the blood flow in the vessels of the heart.

• Rotational, Orbital, or Laser Atherectomy - This technique is performed to remove plaque and calcium from the artery.

• Balloon Angioplasty - Cutting, scoring, or high-pressure balloon angioplasty is performed to push plaque and calcium against the walls of the artery.

• Coronary Artery Bypass Graft Surgery - Coronary artery bypass graft surgery is performed in patients with severe calcification based on intravascular ultrasound.

• Drug-eluting Stent - A drug-eluting drug is coated with medications like Paclitaxel. It slowly releases the drug and prevents the formation of blood clots. It reduces restenosis in patients with coronary artery calcification.

The presence of coronary artery calcification makes it difficult to perform percutaneous coronary intervention during cardiac catheterization.

Conclusion

Coronary artery calcification is common in elderly people and those with coronary artery disease. The risk of coronary artery calcification can be reduced by treating the risk factors such as diabetes mellitus, hypertension, kidney disease, and abnormal cholesterol levels. Early diagnosis and treatment are essential to prevent the risk of complications. Eating foods low in fat, doing regular exercises, maintaining blood pressure and cholesterol levels, and avoiding tobacco products can help maintain cardiovascular health.