There’s good news for cardiac patients requiring implantation of drug-eluting stents (DES).

According to experts, the introduction of second-generation DES has drastically reduced chances of restenosis (artery getting blocked again) and late stent thrombosis (blood clotting inside the stent).

“Recent studies have shown that there is a probability — though not high — of late stent thrombosis after implantation of first-generation DES. The second-generation stents have brought down the chances significantly,” stated Shuvo Dutta, director of interventional cardiology department at BM Birla Heart Research Centre.

Instead of stainless steel, stents are now being made of less toxic cobalt chromium alloy. The second-generation stents are also thinner than the first-generation ones. “It is easier to place into the artery and it gets covered by healthy healing tissues without any complications,” explained a doctor.

According to cardiologists, about 25 per cent patients who received bare metal stents used to suffer from restenosis. The rate was brought down to less than 10 per cent even among users of first-generation DES, said Dutta. “The figure has fallen further with the use of second-generation stents.”

The subject was discussed at the Second Asian Interventional Cardiovascular Therapeutics in New Delhi recently, added Dutta.

Stents are generally used in combination with or following an angioplasty — a procedure in which a tiny balloon is inflated inside a blocked artery to push the excess plaque or fatty deposits against the vessel wall to unclog the blockage and facilitate blood flow.

During angioplasty, a stent is mounted on the balloon and placed inside the vessel to ensure that it does not close.

A drug-eluting stent is designed to allow the release of a drug into the coronary artery to slow the multiplication of cells around the stent and ensure that the vessel heals normally. “When the balloon is inflated inside the blood vessel, the muscle suffers an injury and this activates the multiplication of its cells. There is a chance of the vessel getting choked within a period of six months,” explained chief of cardiology and director of the Cath Lab at Apollo Gleneagles Hospitals Rabin Chakraborty.

First-generation DES were coated with polymer mixed with drug. The drug is released from the polymer over a period of six to 12 weeks. “Although cases of restenosis had been brought down, there were some complaints of patients suffering from late stent thrombosis,” said Dutta.

According to an estimate, about two per cent of the patients who had first-generation DES implanted suffered from late stent thrombosis. One of the main reasons was that these patients had stopped taking anti-thrombosis pills.

“The second-generation DES reduce the risk of thrombosis,” asserted Chakraborty. “But it is imperative for the patients to continue with the anti-thrombosis drug, till the doctor says it is okay to stop taking it,” he warned.