Drug eluting stents are not dangerous, say experts
New Delhi, Oct 29: The world's first totally absorbable Drug Eluting Stent (DES) for heart treatment has been proved effective, feasible and safe, according to noted interventional cardiologist Deepak Natarajan of Apollo hospital.
This was presented at the ongoing Washington Transcatheter Cardiovascular Therapeutics conference, he said.
''This stent would represent the best of both worlds by releasing a drug to prevent reblockage of the heart vessel and would then actually disappear in a few months to make the risk of late stent clots nonexistent'', he told UNI.
The controversy over the impact of the DES was causing concern, but the stunning data presented in the recent World Cardiology conference held in Barcelona, Spain, had strongly suggested that late clots (stent thrombosis) in stents were not common.The newer class of stents are similar to Bare Metal Stents (BMS), as both were wire mesh tubes made of metal. But DES is covered with a plastic called polymer laced with a specific anti clogging drug called rapamycin or paclitaxel.
The older BMS had an unacceptable high rate of reclogging of the coronary artery and this was particularly seen in diabetics and in patients with very narrow arteries, Dr Natarajan said. The launch of DES in 2002 was seen as a major boon because these stents reduced the rate of reclogging from 25 per cent to only six per cent.
Though the newer DES lessened restenosis significantly, they delayed healing of the vessel wall.The delayed healing, largely due to fatal blood clots within the deployed stent, many months to a couple of years post following the procedure. This problem was also present with BMS but to a far lesser degree and for a shorter duration following intervention, he said.
The Washington conference on interventioanl cardiology, the largest in the world, is expected to give guidelines on the usage of pills (aspirin or clopidogrel), to prevent late stent clots. Aspirin and clopidogrel, technically termed as anti-platelet drugs, can keep blood thin enough to safeguard against the devastating clots, he said.
Registers maintained at Bern and Rotterdam cities show that only 23 per cent of patients with DES were on both these pills after a month and in fact 24 per cnt were on neither few months following stenting. More patients stay on both pills for as long as possible. If dual antiplatelet administration is persisted for a longer duration, it is better.
Very old people, however, should not be candidates for DES as they may require non heart related surgery needing stopping of blood thinners, Dr Natarajan said.Technical indications, experience and prudence should dictate selection of the right kind of stent in a patient.
''The correct step would be to steadily move ahead and not peer back to the BMS era. The reassuring news is that more recent versions of DES are constantly jumping from the drawing boards to human trials with spectacular success. Newer drugs are being tried.
The plastic has been modified to melt away within a few months.
Newer structural designs will allow future stents to store and deliver two different drugs simultaneously'', he said.
Moreover, two new meta analysis (pooled data) presented in Washington on Friday has reassuringly resolved that there is no significant difference in stent clots between DES and BMS. This has also been given further boost by a new definition of stent clots which insists on angiographic or autopsy confirmation, Dr Natarajan said.