What Are the Surgical Treatments for Angina and Coronary Artery Disease?

To date, surgery is usually recommended for patients who have unstable angina that does not respond promptly to medical treatment, who have severe recurrent episodes that last more than 20 minutes, or who have other high risk factors for heart attacks. Surgery is also performed in people with severe coronary artery disease (e.g., severe angina, multi-vessel involvement, evidence of ischemia), particularly if abnormalities are evident in the left ventricle of the heart, the main pumping chamber.

Choosing a Procedure

A number of invasive techniques are available for treating coronary artery disease. The two standard surgical procedures are coronary artery bypass grafting and percutaneous transluminal coronary angioplasty. Studies have generally reported similar effectiveness in the two procedures, although one or the other may be preferable for specific patients. Angioplasty is less invasive than bypass and initially less expensive, although the postoperative need for more medications and the high risk for repeat procedures to reopen the artery reduce the long-term difference in cost. It should be noted, however, that bypass is still preferred for certain patient groups. It is the appropriate procedure for patients with three or more blocked arteries, if the left main artery is narrowed by 50% or more, and when the diseased portion of the artery is very long. Patients with diabetes have a significantly better long-term survival rate with bypass surgery than with angioplasty and some experts believe angioplasty should rarely, if ever, be used for these patients. The elderly also do better with bypass surgery, although angioplasty rates are improving in this group. Women have a higher mortality rate than men after either procedure, perhaps because they tend to be older and sicker when they have a heart operation.

Coronary Artery Bypass Graft Surgery (CABG)

Coronary artery bypass graft surgery (CABG) involves taking large blood vessels from the patient's chest, stomach, or leg and grafting them in front of and beyond the blocked arteries, so the blood flows through the new graft around the blockage. The operation is very invasive, requiring opening the chest, routing blood through a lung-heart machine, stopping and then restarting the heart, and transplanting new vessels. Most people are hospitalized for at least a week and do not return to full activity for at least two months. Bypass surgery is very effective in relieving angina and is now improving mortality rates. Grafts taken from arteries in the chest wall and from the abdomen are showing more favorable long-term outcomes than the more traditional approach of taking grafts from two arteries in the chest and the saphenous vein (a long vein in the leg). Bypass operations that use the three arterial grafts are very complicated, however, and only skilled surgeons should undertake them.

Under the best circumstances, bypass surgery carries about a 1% operative mortality rate and the average is 3%. A very common complication is atrial fibrillation, which causes very fast and irregular heart beats and puts people at risk for stroke. Other serious post-operative complications are clots that form in the new graft, closing it up. Therapy with anti-clotting drugs help keep the graft open and working properly. For long-term prevent of closure as well as slowing progression of atherosclerosis, aggressive use of cholesterol-lowering drugs may be more beneficial than the standard anti-clotting drugs. Of some concern was one study reporting that 23% of patients experienced some mental impairment five years after bypass surgery; this warrants further investigation.

Minimally Invasive Bypass.

 Minimally invasive bypass (also called buttonhole or keyhole bypass) surgeries are exciting advances in basic bypass surgery that are currently being tested with good success. One uses a four-inch incision, and the surgeon works on the front of the heart while it is beating slowly. With another, the heart is stopped; fiberoptic scopes and instruments are passed through a number of finger-sized incisions and the surgeon works on all sides of the heart guided by a video image from a tiny camera inserted through a four-inch incision. Early results show that minimally invasive bypass procedures will be less expensive, require a shorter hospital stay, and be a significant improvement over conventional coronary artery bypass surgery. To date, they are performed only in a few medical centers for select candidates.

Angioplasty and Coronary Stents

Percutaneous transluminal coronary angioplasty (PTCA), usually simply called angioplasty, uses a fiber optic camera to guide a catheter directly to the blocked vessel. The physician then opens the vessel using one of several methods. In balloon angioplasty, the surgeon passes a tiny deflated balloon through the catheter to the vessel. The balloon is inflated to compress the plaque against the walls of the artery, flattening it out so that blood can once again flow through the blood vessel freely. In order to keep the artery open, surgeons now commonly employ a device called a coronary stent, which is an expandable metal mesh tube that is implanted during angioplasty at the site of the blockage. Once in place, the stent pushes against the wall of the artery to keep it open. A number of studies are reporting fewer future heart attacks and restenosis in patients who receive stents compared with those who had angioplasty alone. Of great interest, in fact, is increasing evidence that in certain patients the risk for future heart attacks and restenosis may be cut significantly when a coronary stent is used as the initial device after a heart attack instead of balloon angioplasty.

Angioplasty is less invasive than bypass surgery, requiring only one night in the hospital; recuperation takes about a week. It should be pointed out the chest pain after the procedure is very common and usually due to problems other than ischemia. Chest pain is more common when a stent is used, possibly because the artery is stretched.

Preventing Blood Clots.

The most common serious complication that occurs during or shortly after angioplasty is reclosure of the artery, often but not always because of blood clots. Aspirin, heparin, or combinations of anti-clotting drugs are generally used during and after the operation. Aspirin is more effective than heparin. The new anti-clotting agents tirofiban, abciximab, argatroban, or bivalirudin may be more effective for preventing reclosure, often when administered in combination with heparin or aspirin. Anti-clotting drugs are not wholly protective, in any case, because reclosure in some cases is due to other, unknown causes.

Preventing Restenosis.

Narrowing or reclosing of the artery (restenosis) occurs within a year of angioplasty in nearly half of angioplasty patients, often requiring a repeat operation. So far, no anti-clotting or anticoagulant agents, even some of the newer ones, such as abciximab, are useful in preventing this puzzling effect, which is not due to blood clots forming in the opening but might be caused by smooth-muscle overgrowth in the blood vessels. Some evidence suggests that the release of large amounts of oxidants (damaging unstable particles) at the surgical site activates genetic changes in certain white blood cells that may cause smooth muscle growth. With this theory in mind, researchers have tested an antioxidant drug, probucol (Lorelco) and reported that the drug significantly reduced restenosis. Antioxidant vitamins E and C and beta carotene did not provide any protection against restenosis in the same study, but doses may have been too low. Other drugs that are being investigated for their ability to limit smooth muscle growth include verapamil, a calcium channel blocker and a protein called angiopeptin. Some experts argue that smooth muscle growth may not even be the major culprit in restenosis, but that other activities, such as scarring, that remodel and narrow the blood vessels may be major factors.

Radiation treatment of the site is also used to prevent reclosure, although some experts are concerned about its safety. A 1999 study reported a higher incidence of blockage occuring after angioplasty within two to 15 months in patients who had also received radiation treatments than in those who did not.

Patients with unstable angina and the very elderly are at particular risk for failure during and shortly after angioplasty. One medical center reported, however, that such patients had a long-term survival rate equal to their peers without these conditions. The overall five-year survival rate for patients who have angioplasties, including repeat procedures to correct stenosis, is as high as 90%, and the ten-year survival rate is over 75%.

Directional Atherectomy

Directional atherectomy has been another attempt to solve the problem of reocclusion of the blood vessels. A balloon catheter is inserted for determining position; then, a tiny cutter spinning at 2,500 rpm removes plaque fragments from the arterial walls. The use of angioplasty with the coronary artery stent, however, is proving to be safer and more effective.

Transmyocardial Revascularization

Lasers have been used with both angioplasty and bypass procedures but the risks have been high and the treatment is expensive. One laser procedure called transmyocardial laser revascularization (TMLR) applies laser energy directly to areas in the heart where blockage has occurred and creates 10 to 50 tiny channels. It has been approved for patients with severe angina who do not respond to other treatments. A number of studies are showing that the procedure improves quality of life and reduces anginal pain. One reported, however, that improvements were insignificant for patients with severe angina and after a year, survival rates were lower in those who had TMLR (89%) compared to patients taking medications (96%). Experience with this procedure is still limited, and more studies are required to determine if TMLR is any more effective than medications. The procedure itself carries some risks for complications, including some that can be life-threatening. New laser techniques may help reduce these problems.

Enhanced External Counterpulsation (EECP)

A noninvasive technique called enhanced external counterpulsation (EECP) has been used successfully by over a million people in China and is currently in trials in the US. The technique uses an air pump that inflates and deflates pressurized cuffs around the legs, causing blood to be pushed into the heart. It also appears to produce actual cellular changes that benefit the heart. In one study, it relieved angina in 74% of patients who used it; those with three diseased vessels, however, did less well, and the procedure is not appropriate for those with heart failure or blood clots in the legs. EECP will not be likely to replace angioplasty or bypass, but it may reduce the need for nitrates and is proving to provide long lasting benefits.