Medical advancements in heart health-care

The Edwards SAPIEN valve is placed via a leg incision and expanded with a balloon.
The Edwards SAPIEN valve is placed via a leg incision and expanded with a balloon.
Posted: February 02, 2014

Since the 1960s, the number of people dying from heart disease has fallen steadily in the United States. But heart disease is still responsible for a quarter of all deaths, and remains the leading cause of mortality for both men and women. Innovations in care and more insight into risk factors has helped lessen its damaging impact.

One insight is that many people can control their risk. Most heart disease is preventable, but "we don't pay attention to that disease process" until it's too advanced, said Daniel Edmundowicz, medical director of the Temple Heart and Vascular Institute in North Philadelphia. "We have to start much earlier if we're going to impact this disease."

Getting people to eat better and move more remains a supreme challenge. "Statins have probably done more to reduce cardiovascular risk than anything we've done in the last 20 years," said Perry Weinstock, director of Cooper Heart Institute in Camden, referring to drugs known for reducing cholesterol. "That's not a proud statement - I wish people would change their diet and exercise, but they don't."

What follows is a brief overview of five new developments that patients should know about.

A new class of cholesterol drugs is emerging, niacin has lost some luster, and revamped cholesterol guidelines have stirred debate. Also, researchers find links between the bacteria in our gut, red meat, and heart disease. And open-heart surgery for a heart-valve replacement may soon be a thing of the past.

Cholesterol guidelines. The American Heart Association's new guidelines for cholesterol - designed to help prevent heart disease and stroke - stirred controversy after their release in November. The focus on patients' heart risk represented a radical departure from past guidelines, which were strictly number-based targets.

The guidelines also push aggressively for the use of cholesterol-lowering statin drugs, leading some doctors to predict a gross overprescription of the class. An online risk calculator takes into account age, gender, blood pressure, and other factors to calculate a given patient's likelihood of having a heart attack or stroke within the next 10 years. If risk is at 7.5 percent or higher, then the report recommends getting the patient on statins. This is in contrast to the 2002 cholesterol guideline, which suggested statins only if risk exceeded 20 percent.

The new calculator was also challenged for possibly overestimating risk. Main Line Health cardiologist Thomas Phiambolis said that patients should be careful, because such population-based risk calculators don't always perform well for individuals.

The current calculator is somewhat crude, agreed cardiologist Adam Cohen of Abington Medical Specialists. "We're still at a phase of medicine where we're using rather blunt tools; I think it's going to evolve." Future risk estimation could be more individualized and take account of a patient's genetic makeup.

"This is a start, it's an imperfect start, but it's an important beginning toward patient-centered treatment," he added.

PCSK9 inhibitors. Physicians remain enthusiastic about an emerging class of drugs, called PCSK9 inhibitors, that promise to lower cholesterol with or without statins.

While statins have been the first line of defense for high cholesterol and have worked well for millions of patients, a small but significant number have a drug allergy or side effects, such as leg cramps and memory problems. For others, statins don't lower LDL, the "bad" cholesterol, enough.

That's where PCSK9 inhibitors may help. The family of drugs, still in trials, has cut LDL cholesterol an additional 50 percent or more in patients already on statins. But long-term trials are needed to show efficacy in improving heart risk and outcomes.

"Certainly, they are living up to their promise in lowering LDL," said Penn Medicine cardiologist Daniel Rader. "The excitement about this class has continued to build."

Despite its bad reputation, some cholesterol is needed by our bodies. Most of the waxlike substance is made by our liver and other cells, while the rest comes from the animal products we eat.

PCSK9 inhibitors are man-made antibodies that target PCSK9, a protein that keeps the body from removing artery-blocking LDL cholesterol from the bloodstream. In contrast, statins inhibit an enzyme that controls cholesterol production in the liver.

Pfizer, Amgen, and Regeneron are all developing versions. A possible deterrent for patients is that the drug must be injected every two to four weeks.

Focus on gut microbes. Is red meat bad for your heart? Maybe, but the usual suspects - cholesterol and saturated fat - may not be to blame. The culprits could be the bacteria in your gut.

Researchers are paying close attention to the intestinal microbiome, linking our guts' bacteria to obesity, diabetes, and even cancer. Now a study in mice has found that a molecule called carnitine, abundant in red meat, can be digested by microbes in a way that speeds hardening of the arteries.

While heart patients are typically warned against eating too much red meat, there was never a satisfying explanation as to why. Doctors hope that the recent investigations into the microbiome might fill in some of those blanks.

Eating red meat can cause a chain of chemical events that raises levels of TMAO, a substance in the blood that has been linked with heart disease. But after some subjects were given broad-spectrum antibiotics for a week, the TMAO levels fell despite eating steaks. So red meat seems to need bacteria to make TMAO.

"This is a whole different mechanism where red meat may contribute to heart disease," said Rader. He wonders whether the microbiome could then be altered, so that we may all eat steaks without heart consequences.

"This is a very exciting area, but not a well-understood area," said Cooper Hospital's Weinstock. "We have to let it play out a little bit more before we jump on that bandwagon."

Niacin not so helpful. Niacin has long been a mainstay for improving cholesterol levels. But with the results of a new study that failed to show its effectiveness, the vitamin is falling out of favor.

"Niacin has gone from a boutique product that was used by a lot of physicians, to something that just isn't used that much anymore," said Rader.

In March, a trial from Oxford University, covering 25,673 patients, found that niacin did not prevent heart attacks and strokes. Patients on niacin also had more bleeding, infections, and diabetic complications than the placebo group. It was the largest study of niacin ever done. During niacin's heyday, decades ago before the advent of statins, a large study fostered enthusiasm about its effects, lowering bad cholesterol and raising good cholesterol.

"Everybody thought that it might be the magic bullet," said Weinstock. The problem was that the improved cholesterol numbers did not lead to better patient outcomes and less incidence of heart disease.

"People have lost a lot of their enthusiasm for it," said Main Line Health cardiologist Peter Kowey. Niacin also has unpleasant side effects, such as flushing and itching.

Transcatheter aortic valve replacement. An aortic valve narrowed by plaque buildup means the heart has to pump harder - leading to chest pain, fatigue, and even heart failure - but replacing the valve once required risking open-heart surgery. Now more patients are avoiding the chest-cracking operation for a minimally invasive option, transcatheter aortic valve replacement.

The TAVR procedure involves feeding a small, crimped artificial valve through a catheter that is threaded through the patient's blood vessels into the aorta. Once there, the valve is expanded by inflating a balloon that fits the new device in place of the faulty valve, where it starts working immediately. The catheter is inserted through a small incision in the groin or between the ribs, and involves less injury and recovery time than the surgical method.

In November, a study from the Society of Thoracic Surgeons involving 7,710 aortic stenosis patients, found that TAVR can be an effective and safe option to open-heart surgery. Using patients from a national registry, it found that 92 percent had successful implantation of a new valve with a low rate of death and stroke.

"The results are very, very good, much better than we anticipated," said Main Line Health cardiac surgeon Scott Goldman.

The Food and Drug Administration approved the first TAVR device, the Edwards SAPIEN, in 2011 for patients considered "inoperable," such as the elderly. Since then, approval has been expanded to high-risk patients as well as to a self-expanding valve from Medtronic, the CoreValve.

"We're moving down the spectrum of risk," said Penn Medicine cardiologist Howard Herrmann. "The next hurdle is to prove we can be as good as surgery in patients that are low-risk."


meeri.kim@gmail.com

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