The history of clearing clogged coronary arteries and implanting is one of progress and setbacks:

1960s: Coronary artery bypass grafting surgery (CABG) is introduced to repair arteries clogged with plaque. Surgeons harvest healthy veins from a patient’s legs and transplant them around blocked arteries near the heart, restoring blood flow.

The problem: Although effective, it’s a major operation. Surgeons saw through the patient’s sternum and pry open the rib cage. About 500,000 such surgeries a year are performed.

1977: Doctors begin to unclog arteries with balloon angioplasty. They make a small slit in the patient’s groin, run a wire-like catheter up the femoral artery and inflate a tiny balloon inside the plaque blockage, opening it, restoring blood flow.

The problem: Within six months, one-third to one-half of patients experience a re-narrowing of the artery due to plaque, called “restenosis.”

1986: Pharmaceutical companies bring out the “bare-metal stent” a tiny metal-mesh sleeve that is collapsed, run up the femoral artery to the plaque lesion, expanded by the balloon and left to keep the artery open.

The problem: In 15 percent to 30 percent of cases, restenosis still occurred within a year.

The reason: Ideally, when a wire-mesh is implanted, the artery heals it over in a few months with smooth muscle cells called endothelia. But in some cases, the cells grow back too aggressively, piling up into scar tissue, narrowing the artery again and encouraging a new blockage with plaque.

2003: The “drug-eluting stent” arrives. It’s coated with medicine that is released over a month or more to slow the growth of the cells that encourage restenosis. They were a hit - cutting re-blockage by two-thirds.

The problem: Occasionally a patient with a drug-eluting stent suffers a heart attack, and sometimes it’s fatal. Studies say it happens more often with drug-eluting stents than with bare-metal stents. It isn’t restenosis; it’s thrombosis, a sudden blood clot that forms inside the drug-eluting stent.

The reason: While the drug-eluting stent is time-releasing its drugs, it effectively stops the re-growth of muscle cells inside the stent.Thus, the bloodstream reacts to the foreign metal object - the bare stent - the same way the blood in your cheek reacts to the nick of a razor - it clots. Result: a heart attack.

Today the debate rages on; doctors in favor of creating better stents vs. doctors who would forgo angioplasty altogether in favor of open-heart surgery.

Sources: Fred Tasker - McClatchy Newspapers, Ohio.com