Heart experts warn on safety of drug-coated stents

BARCELONA, Sep 4 (Reuters) Drug-coated stents -- tiny, wire-mesh tubes used to prop open diseased arteries -- may increase the risk of potentially fatal blood clots, researchers said.

Up to 6 million patients worldwide have received coated, or ''drug-eluting,'' stents since they were launched in 2002, creating a 5-billion dollars-a-year business for market leaders Boston Scientific Corp and Johnson&Johnson researchers said yesterday.

But a meta analysis of results from past clinical trials of first-generation, drug-coated stents presented at the World Congress of Cardiology showed these patients had a greater risk of heart attack or death than patients given a bare metal stent.

The increased relative risk was greatest for J&J's Cypher stent, at a statistically significant 38 percent, said Dr Edoardo Camenzind of Geneva's University Hospital.

For Boston Scientific's Taxus stent the increased risk was 16 percent, but this did not meet statistical significance.

The actual risk of death or heart attack was still low in both groups, at 6.3 per cent for patients given Cypher and 2.6 per cent for Taxus. But because drug-coated stents are so widely used, thousands of patients could be affected.

Dr Salim Yusuf of Canada's McMaster University said the findings were ''disconcerting.'' Drug coating has proved hugely popular because it prevents arterial scarring after a stent is implanted, which may cause arteries to narrow again in a process known as restenosis.

However, the drug coating delays healing round the stent, creating a risk of clots forming, which can trigger a heart attack.

The real worry is what happens after a year or more, with evidence growing that the risk of late stent thrombosis continues long after original treatment.

Late stent thrombosis has emerged as a major issue at the conference and a majority of doctors, during a session on stents, raised their hands when asked if they saw it as a problem.

The latest research follows an earlier Swiss study that found the rate of heart attacks and deaths was more than three times higher in patients with drug-coated stents who stopped taking blood-thinning drugs than those who had bare-metal ones.

Drugs like aspirin and Sanofi-Aventis SA's Plavix are generally prescribed for a few months for patients given drug-coated stents but cardiologists are now debating whether they should be given longer term to prevent thrombosis.

Denis Donohue, vice-president of clinical and regulatory affairs at J&J's Cordis devices unit, said late stent thrombosis was an issue but there was not a clear safety signal.

The company's own data showed long-term mortality rates of 6.5 per cent for patients with a Cypher stent against 5.1 per cent for bare metal stents, but this was not a statistically significant difference.

Reuters KR DB0900