Revascularization: Bypass Surgery and Angioplasty

Revascularization can also be accomplished using percutaneous transluminal coronary angioplasty (PTCA), which is much less invasive. This is done using catheters, which are passed through the femoral or brachial arteries to the heart, as with coronary angiography. Wires are then passed through the catheter and down the coronary arteries past the narrowings. A balloon, which is deflated, is passed over the wire to the point of greatest narrowing. The balloon is then inflated, compressing the plaque or obstruction. When the balloon is deflated, the artery usually remains open. Blood thinners are used to prevent immediate clotting while the area heals over, and oral antiplatelet agents also prevent blood clots from forming on the torn or damaged artery. Twenty to 30 percent of arteries reocclude following the procedure, with up to one-half of these occurring in the first twenty-four hours. While many of these can be reopened with a balloon and kept open using a coil or stent, occasionally a dissection or acute closure results in Figure 4 The Heart: Lysis of Clot SOURCE: Suggested by brochure issued by Pfizer Canada Inc. (1996) and created by Symphony Medical Communications of Oslo, Norway (1996). the need for emergency surgery. These complications are more common in the elderly. Gregorio, Kobayashi, Albiero, et al. found that 3.7 percent of angioplasty patients over the age of seventy-five required emergency CABG, compared with 1.4 percent for those under the age of seventy-five. They also found that mortality was markedly increased, at 2.2 percent for the older patients, compared with 0.1 percent for the younger group. This procedure is very operator-dependent, and experience certainly results in better outcomes. While complication rates are lower than for bypass surgery, they are more significant with increasing age. Bypass surgery results in more complete revascularization and better reduction of symptoms than PTCA, but it has not been shown to prolong survival. Diabetics, the BARI (Bypass Angioplasty Revascularization Investigation) trial showed, have had improved five-year mortality with bypass surgery compared to angioplasty (5.8 percent vs. 20.6 percent).

The most striking difference between the two procedures is the need for repeat revascularization Figure 5 The Heart: Percutaneous Transluminal Coronary Angioplasty (PTCA) SOURCE: Suggested by brochure issued by Pfizer Canada Inc. (1996) and created by Symphony Medical Communications of Oslo, Norway (1996). procedures. Less than 10 percent of bypass surgery patients require another procedure in five years, compared to 50 percent of angioplasty patients. Further, not all blockages are amenable to angioplasty. Experience of the physician performing the angioplasty (interventionalist) is critical with more difficult lesions.

Following angioplasty or coronary artery bypass grafting, risk management is important to maintain artery patency. This includes the use of aspirin and antiplatelet agents, aggressive lipid lowering, smoking cessation, and managing blood pressure and diabetes. Revascularization may reduce the need for antianginal medication. These treatments should not be considered curative; patients must still be aware of the possibility of recurrence of angina and ischemic heart disease.

The utilization of coronary angiography and subsequent revascularization varies considerably within different jurisdictions and health care systems. An interesting study compared patients over the age of sixty-five having a heart attack from a United States Medicare database and an Ontario, Canada database. Catheterization rates in the United States approached 40 percent, compared to 10 percent in Ontario, and revascularization rates were 28.5 percent versus 6.3 percent, respectively. Despite this marked increase in revascularization in the United States, mortality rates at one year were identical. Symptom control was not assessed, however.

In summary, while ischemic heart disease and associated risks increase with increasing age, there is also increased risk with revascularization procedures. In addition, comorbidities such as diabetes, hypertension, renal failure, prior strokes, lung disease, heart failure, and deconditioning may also be increased with increasing age. If medical therapy cannot adequately control symptoms of ischemic heart disease, then revascularization procedures must be considered. While angioplasty carries less risk, it is not always technically possible, and the need for repeat procedures is greater than with bypass surgery. Bypass surgery carries far greater risk but may provide the greatest benefit. Further, there seems to be an increasing physiological variability with aging. Multiple organ systems are at risk during bypass surgery and complications may be more devastating if coping skills and general health are reduced. There is no substitution for an open and frank discussion with physicians and family before embarking on revascularization. Technical expertise of surgeons, physicians, and the entire health care team are crucial to achieve optimal outcomes.