Coronary Artery Disease and Angina
DescriptionAn in-depth report on the causes, diagnosis, treatment, and prevention of CAD.
Alternative NamesAngina; Angiography; Angioplasty; Atherosclerosis; Beta Blockers; Calcium Channel Blockers; Coronary Artery Bypass Surgery; Coronary Artery Disease
Angioplasty and Stents
Percutaneous transluminal coronary angioplasty (PTCA), usually simply called angioplasty, involves opening the blocked artery.
Complications occur in about 10% of patients (about 80% within the first day). In one report of 53 European and Canadian medical centers, the mortality rate from all causes four years after PTCA was 4.1% Outcomes are better in hospital settings with experienced teams and backup.
The most important long-term complication is reclosure (restenosis), which can lead to heart attack if not treated with a repeat procedure. Stenting and other advances have helped significantly in preventing reclosure and reducing heart attack rates. Nevertheless, a repeat procedure is still needed to restore the opening in 10% to 15% of procedures that use stents. Radiation therapies and stents coated with immunosuppressive agents may significantly reduce these rates.
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. Mild chest pain is even more common when a stent is used, possibly because the artery is stretched.
Preventing Reclosure and Blockage During or Shortly after Angioplasty
Reclosure of the artery during or shortly after angioplasty often occurs. A number of anti-clotting agents are used to help prevent this, although they are not wholly protective because reclosure in some cases is due to other, unknown causes.
All of these agents, pose a risk for bleeding complications.
Preventing Artery Narrowing (Restenosis) Over Time
Narrowing or reclosing of the artery (restenosis) can occur within a year of angioplasty or even longer in between 15% and 60% of angioplasty patients. Coronary stents, anti-clotting agents, and other advances have reduced these events significantly, but have not eliminated the problem. Theories for the cause of restenosis include the following:
Symptoms of restenosis include chest pain on exertion. (Heart attacks, however, do not usually occur with such events.) The narrowing of the artery in this case is not due to blood clots and so anti-clotting agents are not useful. Restenosis usually requires a repeat operation. A number of approaches, mostly investigative, have been developed to prevent restenosis after angioplasty.
Sirolimus- and Other Drug-Coated Stents. Stents coated with the drug sirolimus (Rapamune), also called rapamycin, are generating great excitement. This agent dampens immune factors that cause cell proliferation and inflammation and it also has antibiotic properties. In an important 2002 study, none of the patients who were given the coated stent experienced reclosure and 94% of them were free of any adverse heart events. In comparison, 27% of patients in the noncoated group experienced restenosis and only 71% of them were free of adverse heart events. Although long-term side effects remain unknown, some experts believe this advance will revolutionize heart treatments. Other drug coatings under investigation include paclitaxel.
Coronary Artery Brachytherapy. Radiation treatment called coronary artery brachytherapy (Gamma One, Beta-Cath) can inhibit cell growth in the arteries responsible for restenosis. With this approach, any blockage in the stent is first removed, and a tube with an inflatable balloon is inserted. The surgeon then implants a temporary device that delivers radiation. Brachytherapy is showing excellent results in preventing restenosis and significantly reducing heart events and improving survival. Brachytherapy is also showing promise in preventing restenosis in stented artery grafts that were put in place after bypass surgery and later failed.
There are still many outstanding safety issues with these treatments, however, that will only be answered with long-term use. For example, one 2002 study reported a possibly higher risk for blood clotting. It should be noted that once radiation is performed, stents cannot be replaced again.
Medications. A number of medications are being studied for prevention of restenosis, although benefits to date have been modest. Other agents under investigation include statins, various anti-clotting agents, and B vitamins.
Other Procedures. Other procedures under investigation to keep the arteries open use ultrasound "soft" x-rays, and cryotherapy (very low temperatures).