Despite the fact that more people are making healthier lifestyle decisions than ever before, cardiovascular disease remains the leading cause of death worldwide.

Heart disease has a number of underlying causes: The heart might not pump as strongly as it should, which can lead to heart failure; it beats in an irregular rhythm known as arrhythmia; or the heart’s valves don’t open and close properly.

But the leading cause of heart disease is atherosclerosis, which occurs when fatty deposits known as plaques build up on the walls of arteries. This narrows the channel through which blood flows, making the heart work harder to move the same volume of blood. Over time, the excess effort can wear out the muscle or, in the worst-case scenario, part of a plaque can break off and block an artery, triggering a heart attack or stroke.

Although the incidence of heart disease has dropped somewhat over the past few decades, it’s still the leading cause of death in the US. According to data from the US Centers for Disease Control and Prevention, heart disease killed nearly 600,000 people in 2010 (the latest year for which data are available), while stroke caused roughly 130,000 deaths.

And on a global basis, the story is much the same: Nearly 30 percent of deaths worldwide were attributed to heart disease, making it the number one killer.

Given these grim statistics, substantial time, money and research will continue to be devoted to addressing the underlying biological mechanisms by which cardiovascular disease progresses.

Faulty heart valves, known as valvular heart disease, can result from congenital defects, but valves can also be damaged by illness, such as rheumatic fever or strep infections. Regardless of the cause, nearly 5 million Americans are diagnosed with valvular heart disease each year.

A month ago, I wrote about Edwards Lifesciences Corp (NYSE: EW), which makes devices that improve the function of heart valves or can replace them entirely. Its products are used in cardiac bypass and stent procedures, which involve rerouting blood flow around affected arteries or using a small mesh tube to widen a narrowed artery. Edwards also makes equipment used for hemodynamic monitoring.

One of the company’s most innovative products is its transcatheter heart valve, which can replace damaged or faulty valves that control blood flow through the heart.

Until recently, valve replacement necessitated open-heart surgery, which can cost in excess of $100,000 and requires both a lengthy stay in intensive care and a prolonged recovery period. But Edwards’ transcatheter valve can be implanted using minimally invasive surgical techniques that require just a two-day hospital stay and can be performed for as little as a third of the cost of open-heart surgery.

Edwards’ transcatheter valve is one of the safest and most effective products available, and it also provides significant cost savings and potentially better outcomes. Since doctors and hospitals will increasingly see their reimbursement levels tied to outcomes and performance, they’ll obviously opt for the best product out there.

And with more patients having insurance coverage, detection of potentially deadly valve-related problems will occur sooner, which means greater demand for Edwards’ life-saving products.

While faulty heart valves are a serious problem, atherosclerosis is the underlying cause of 75 percent of cardiovascular-related deaths.

There are currently three primary ways of treating atherosclerosis: lifestyle changes via diet and exercise, cholesterol-reducing drugs, or surgical intervention for later stages of the disease.

A number of pharmaceutical companies make cholesterol-lowering drugs such as statins, which inhibit the function of certain enzymes that help the liver produce cholesterol. But statins can have unpleasant and potentially dangerous side effects, such as muscle and liver damage.

Because of that, many doctors recommend that patients with high cholesterol increase their intake of omega-3 fatty acids, which have been shown to reduce the amount of bad cholesterol, while increasing levels of high-density lipoprotein (HDL, or good cholesterol). Another advantage of omega-3s is that they can be easily added to the diet through increased fish consumption or by taking fish oil pills.

However, fish oil pills can be problematic because many contain high levels of docosahexaenoic acid, which can raise triglyceride levels, interfere with commonly prescribed blood pressure medications, or increase bleeding times for patients who take blood thinners.

To address those concerns, Amarin Corp (NSDQ: AMRN), an Irish pharmaceutical company, has developed a process to make omega-3 fatty acids without significant amounts of docosahexaenoic acid.

The drug is called Vascepa, but the US Food and Drug Administration (FDA) has only approved it for use by the small number of patients suffering from high triglycerides. As a result, the company’s earnings have yet to get a real boost from this drug, and its shares have been trading around $10 for the better part of two years now.

But there are two clinical trials underway that could garner approval for Vascepa to be prescribed to a much larger number of patients.

One of the two trials is designed to show whether Vascepa is also effective for patients with lower triglyceride levels than those for whom its use is already approved.

The other trial combines Vascepa with a traditional statin to see if it helps delay a patient’s first “significant cardiovascular event” as well as reduce its severity.

The results of these trials aren’t expected until later this year, but the data released thus far show promise. If successful trials lead to broader FDA approvals, that expands Vascepa’s potential pool of patients to literally millions of people and should create a nice run-up in the stock.

Granted, that’s a catalyst for next year’s earnings, but it makes the shares’ current valuation much more attractive. It also makes the company a potential takeover target, especially if interim data remain positive.

Once a patient is at the point where a more aggressive intervention is required to treat atherosclerosis, they might encounter a machine made by Cardiovascular Systems (NSDQ: CSII).

The company’s atherectomy machines use catheters to remove arterial plaques by blasting them into tiny particles that can be carried off by blood without significantly increasing the risk of heart attack or stroke. Traditional treatments such as a balloon angioplasty–a catheter with a balloon attached that’s threaded through the arteries to the site of the blockage and then inflated to push the blockage open– risk causing a cardiovascular event since the debris created can be quite large. It’s a rare occurrence, but it can happen.

At present, Cardiovascular Systems’ atherectomy machines are approved only for treatment of peripheral artery disease, such as blockages in patients’ extremities.

But the company’s machines are undergoing trials to show that they can be used to safely and effectively treat primary coronary artery disease, or blockages closer to the heart. The company should present data sometime in April, and the device could receive FDA approval by the end of the year. That seems likely since its atherectomy devices have already demonstrated their superiority over many competing devices.

Similar to Amarin Corp, an FDA approval could significantly boost shares of Cardiovascular Systems.