August 1, 2011

Enhancing Blood Supply — Revascularization Procedure Options
By Lindsey Getz
For The Record
Vol. 23 No. 14 P. 24

Physicians can choose from a number of revascularization procedures to enhance patients’ quality of life following a heart attack.

Revascularization following a heart attack constitutes a variety of procedures that help reestablish blood flow to the heart muscle fed by a blocked or narrowed artery. The ideal candidates for revascularization procedures are patients with ongoing angina or ischemia following a heart attack, particularly if a large part of viable heart muscle is at risk. For older patients, it can be a matter of life and death.

When it comes to heart attacks, “Time is muscle,” says Scott R. Sherron, MD, of the Texas Heart Institute at St. Luke’s Episcopal Hospital. “That means the faster an artery is opened, the less permanent muscle damage is done. In fact, a timer starts as soon as a patient arrives, called ‘door-to-balloon time,’ and hospitals and regulatory agencies use this time as a measure of performance.”

The type of revascularization procedure employed depends on the timing and the type of heart attack. One type of heart attack, says Sherron, called an ST elevation myocardial infarction (STEMI), is best treated with emergent heart catheterization and balloon angioplasty or stenting if it can be done within six hours of the onset of symptoms. This is certainly a case where “time is muscle.”

“Other types of heart attacks that are initially treated with medicines present a separate question for revascularization,” says Sherron. “Stenting and other forms of catheter-based treatments and bypass surgery are two different ways to restore blood flow, and each has their own advantages and disadvantages.”

Stenting is a fairly common procedure that uses a wire metal mesh tube to open an artery during angioplasty. “Stents are deployed through catheters placed from the groin and require only a needle stick and minimal anesthesia and are therefore easy to tolerate and have a shorter recovery time,” says Sherron. “However, stents are usually limited to the treatment of one or two vessels and carry the risk of restenosis, which is renarrowing of the artery from scar formation inside the vessel that mainly occurs in the first six months after a stent. The likelihood of restenosis varies, but averages 7% to 8% with current technology.”

Catheter-based aortic valve replacement is another treatment that may be an option, though it’s still making its way through clinical trials in the United States. While it’s not a type of revascularization, it’s an emerging procedure used specifically to address narrowing of the aortic valve.

Essentially, a diseased valve is replaced using only a stent with biologic tissue attached. “This technique is being used more on the elderly than among younger patients as it’s a potential alternative to open heart surgery,” says Mark Katlic, MD, of Geisinger Wyoming Valley Medical Center in Wilkes-Barre, Pa. “In the past, we would have replaced the valve with surgery requiring an incision and putting the patient on a heart/lung machine. That’s a major operation. But some very bright doctors developed a way to put the valve in using a catheter through the groin. Then a new valve is deployed through the diseased valve. Of course you have to do all that without blocking the blood flow to the heart.”

Bypass surgery is more complex than catheter-based procedures and involves redirecting the blood supply around clogged arteries to improve oxygen and blood flow to the heart. “It’s a major surgical procedure and usually uses one artery from the chest wall as well as veins from the leg to provide a detour around the blockages,” explains Sherron. “It is a bigger up-front procedure but allows for treatment of multiple blockages at once and has a lower chance of needing a repeat procedure in the first several years after surgery. It may be the only reasonable option with certain types of blockages.”

Of course all procedures carry some risk. The amount of risk involved in revascularization varies with the type of procedure, says Sherron. “Stenting carries several risks, including a very low risk of stroke, heart attack, or death, as well as the specific risk of damage to a vessel requiring emergency bypass surgery and the risk of needing additional procedures because of scar formation inside the vessel [restenosis],” he says. “Bypass surgery also carries a low risk of stroke, heart attack, or death along with the other risks associated with major surgery, such as anesthesia complications, pneumonia, bleeding, and infection.”

Not a Candidate?
For some patients, these revascularization treatments are not an option. A patient may have undergone a previous bypass, making a second procedure too risky. Or the blockages may be too severe for bypass alone to be effective. Or a patient may simply be too sick for major surgery. In these circumstances, transmyocardial revascularization (TMR) may be considered.

There are several ways to perform TMR, with the least invasive involving the surgeon making an incision on the left side through the ribs to expose the heart, explains cardiothoracic surgeon Bret D. Borchelt, MD, of Forsyth Medical Center in Winston-Salem, N.C. “That allows me to avoid the scar tissue on the front of the heart,” he explains. “I’m also able to avoid the artery that’s used for most bypasses. That’s usually an artery that’s still open and if you damage it in surgery, the patient could die on the table.”

After making the incision using a laser, a surgeon drills small holes from the outside of the heart into its pumping chamber, creating channels along the left side that allow oxygenated blood to immediately go out into the heart muscle or left ventricle, Borchelt explains.

“The idea of TMR is that without the need to put someone on a heart/lung machine as you would with a bypass and making a smaller incision than you would with a bypass, you can still create new channels for the heart muscle,” says Katlic. “It’s something that would be less traumatic for the patient. Some patients aren’t good candidates for other procedures, maybe because the arteries are just too narrowed or diseased. The hope is that with TMR you’re creating another way to open up channels and get oxygenated blood to the muscle.”

While TMR has been shown to work, physicians aren’t completely sure why or how. Borchelt says he was initially skeptical when word of the procedure first spread about 10 years ago. However, once he started seeing data that showed patients with chest pain maintained a reduction in their pain scores five years out, he started getting excited. “Six years ago, I did my first one on a patient who was having chest pain at rest and had already had a previous bypass surgery,” recalls Borchelt. “She wasn’t a good candidate for other procedures, so I decided to try TMR. It was amazing—she now has no chest pain at rest or even mild exertion. It’s been really rewarding and is a procedure I’m still excited about.”

Most patients get at least two reductions in their [pain] score, says Borchelt. A class four, or chest pain at rest, may be able to be reduced to a two or even a one, which can be life changing for the patient. However, one important thing to note, Borchelt adds, is that there’s no proof this will extend a patient’s survival.

“If the patient has bad arteries, this probably isn’t a procedure that’s going to extend their life,” he says. “It’s not repairing anything. However, it will improve their quality of life and that’s important. The patient will be less likely to be readmitted for chest pain and will be able to do things they previously couldn’t do.”

This is a procedure likely to be performed on older patients considering they often have had previous surgeries and may no longer be candidates for future procedures. Though it’s less traumatic than some procedures, there are still situations in which TMR wouldn’t be recommended, says Borchelt. If the heart is too weak, drilling holes may be too much for the muscle to handle. Or if the patient has received radiation treatment to the chest as part of breast cancer treatment, it may make a procedure like TMR too difficult to heal from. In addition, if the patient is not a good candidate for surgery in general because of a condition such as severe chronic obstructive pulmonary disease or other chronic health issues, TMR would not be ideal, says Borchelt.

And it’s important to remember that even though it’s less invasive than open heart surgery, it’s still a major procedure. “I wouldn’t tell patients it’s just an in-and-out thing by any means,” says Borchelt. “We’re still talking heart surgery, and the patient is likely to be in the hospital for about four days recovering. But it’s certainly a less invasive option and for some may be the only option available.”

Revascularization in Older Patients
Overall, heart revascularization procedures have proven quite successful in the aging population. In fact, a recent study published in the Canadian Medical Association Journal found that the use of invasive procedures such as revascularization in elder heart attack patients may be responsible for improved survival rates after one year. It also found that the use of such procedures in the aging population is increasing. That doesn’t mean, however, that all physicians are willing to operate on their oldest patients.

“Unfortunately, ageism still exists and is not going away,” says Katlic. “It may be diminishing some, but in the medical field it’s still an issue. There has been some research published that shows cardiac surgery may not even be discussed with an 80-year-old who has mitral valve disease, probably because the doctor believes the patient is too old. And it’s been shown again and again that elderly cancer patients are not entered into clinical trials or allowed the most aggressive treatment options despite the fact that other research shows they can tolerate it. There’s still this idea that once patients hit a certain age, they’re simply too old for some medical treatments even though research has shown that’s not necessarily the case. There’s a lot more to consider than the patient’s age.”

Katlic says it’s not age that makes a patient a good candidate for surgery—or any other procedure for that matter. It comes down to a patient’s overall condition. “The geriatric population is one of the most variable, so you can’t just come up with an arbitrary number and say it’s too old for surgery,” he says. “There can be one 80-year-old patient who is very frail and has some memory loss and other issues. Another may be an 80-year-old who is running marathons.”

Cardiologists have learned over the years that there are ways to determine who is a good candidate for a procedure and who is not—something physicians need to discuss with a patient and his or her family. When it comes to the geriatric population, it’s important to assess not only patients’ physical condition but also their emotional well-being because studies have shown mental status and mood play a huge role in recovery. “Their overall physical and mental condition should help make the decision on whether they can handle surgery and its subsequent recovery time,” Katlic says.

There are also differences between male and female patients that may come into play, but a patient’s physical condition far outweighs any considerations of sex. “Some of the different considerations for men vs. women in regards to revascularization decisions are mostly driven by anatomic features like vessel size, [which are] usually smaller in women,” says Sherron. “Since women tend to develop heart disease later, they are older and have more comorbid conditions, which may explain the overall higher mortality. However, the actual plaque characteristics are not different in men and women.”

These procedures bring a lot of questions to the table, and the right course of treatment performed in an efficient and timely manner is critical. No matter what the procedure, the overall objective remains the same. “The main goal of any of these procedures is to help people to live normal lives,” says Katlic. “If the patient’s heart is bad, not only will it cause them chest pain, but shortness of breath. That can really limit what they do. The idea is to give them the best quality of life possible and revascularization procedures may be one of the ways to help achieve that goal.”

— Lindsey Getz is a freelance writer based in Royersford, Pa.

Improved Outcomes
A recent study highlights the importance of revascularization, which can be a life-saving procedure for many older adults. Published in the May 2010 issue of Catheterization and Cardiovascular Interventions, the study found that 28.8% of patients with significant coronary artery disease (CAD) who did not undergo complete revascularization had a higher mortality rate than those who did. Cardiologists from the Minneapolis Heart Institute Foundation and the University of Minnesota led the three-year retrospective study and reviewed angiographs and clinical data from 493 patients.

After three years, study participants with incomplete revascularization had a 14.8% mortality risk compared with 6.6% of patients who had complete revascularization. The team also found that patients with incomplete revascularization were older, more often male, and more likely to have hypertension, diabetes, peripheral arterial disease, and a previous history of CAD that included heart attack, percutaneous coronary intervention, and coronary artery bypass grafting.

— LG