Matters of the heart

heart illustration

It is February, and all things red — from roses to dresses — once again are en vogue for Valentine’s Day. But there is another reason to go red this month. The American Heart Association marks it as American Heart Month.

According to the National Heart, Lung and Blood Institute, coronary heart disease is the No. 1 killer in the U.S. The American Heart Association reports that coronary heart disease imposes the highest economic burden of all cardiovascular diseases, coming in at a cost of about $109 billion in treatments, medications and lost productivity each year.

What is coronary heart disease?

The coronary artery supplies nutrients to the heart. Coronary heart disease is the result of atherosclerosis, which is a process of plaque buildup on the coronary artery wall. The plaque, which narrows and hardens the artery, consists of cholesterol, calcium and cellular debris. Obesity, high cholesterol levels (in particular low-density lipoprotein cholesterol), family medical history, smoking and high blood pressure are risk factors. Common symptoms are chest pain, heart palpitations and heart attacks.

How does atherosclerosis cause coronary heart disease?

Saturated fats in diet and obesity-related insulin resistance increase the deposition of LDL-cholesterol molecules on the endothelial lining of the artery wall. Smoking and high blood pressure exacerbate the damage to the endothelium, which secretes pro-inflammatory cytokines to recruit immune cells to scavenge the lipoproteins at the plaque site. The immune cells may get trapped within the plaque and contribute to hardening of the artery. As the blood flow drops, the heart receives less nutrition and cannot pump properly. This causes chest pain or heart palpitations. In extreme cases, the T lymphocytes and macrophages rupture the plaque via collagen-degrading enzymes. The ruptured plaque generates blood clots that block blood flow and cause heart attacks.

What are the recent breakthroughs in atherosclerosis treatment?

A clinical trial called Dual Antiplatelet Therapy proved that prescribing two anti-blood-clotting drugs, thienopyridine (an ADP receptor inhibitor) and aspirin (a prostaglandin inhibitor), for 30 months, rather than one year, lowered the incidence of blood clots in patients who had drug-eluting stents implanted in them. IMPROVE-IT, which stands for “improved reduction of outcomes: vytorin efficacy international trial,” demonstrated that a combination of ezetimibe, a cholesterol-absorption inhibitor, and simvastatin, an inhibitor of cholesterol production, reduced LDL-cholesterol levels and prevented heart attacks more effectively than simvastatin alone. These studies were presented at the American Heart Association meeting held in November.

Indumathi Sridharan Indumathi Sridharan earned her bachelor’s degree in bioinformatics in India. She holds a Ph.D. in molecular biochemistry from Illinois Institute of Technology, Chicago. She did her postdoctoral work in bionanotechnology at Northwestern University.