Safety and Long-Term Results of Coronary Stents Questioned

The results of long-term studies presenting data on restenosis, reintervention, late stent thrombosis, myocardial infarction (MI), and mortality of drug-eluting stents (DES) compared with bare metal stents (BMS), has raised questions regarding their long-term safety and sparked intense discussion.

The discussions were held among key opinion leaders in clinical and interventional cardiology, representatives of industry, and representatives of regulatory bodies, gathered at a consensus conference held during September 2008 in Nice (France) organized by the European Society of Cardiology (ECS; Sophia Antipolis, France), in cooperation with the European Association of Percutaneous Cardiovascular Interventions (EAPCI). The participants gathered to discuss results of studies and reviews announced at the 2006 ESC meeting held in Barcelona (Spain), which pointed out two divergent trends that are difficult to reconcile. The problem was that late DES thrombosis was present in approximately 0.1-0.2% per year in the simple lesions and patients randomized in clinical trials, reaching percentages as high as 0.5-0.6% per year when all-comers were followed up closely in centers with high average complexity of interventions performed; the existing data show this trend to be persistent for the first three to four years after implantation. Paradoxically, however, this increased rate of late thrombosis did not translate into an increase in mortality or incidence of MI, despite the fact that late thromboses are associated in more than two out of three cases with these catastrophic events.

The most likely explanation for this paradox, according to the participants, is that the restenosis and reinterventions are not as benign as previously thought, with restenosis presenting as acute coronary syndromes (ACS) in 20% of cases, often inducing periprocedural complications at the time of retreatment with surgery or angioplasty. The existing data indicate that there are important differences between the various types of stents, with dissimilar mechanical and pharmacological properties and subsequent differences in clinical outcome. Ongoing large-scale trials with second- and third-generation DES have been initiated and the trials have extended their follow-up long enough to support manufacturers' claims of the reduced thrombogenicity of these devices.

According to the ECS, the dark side of the debate was an unjustified alarm when results were presented in the general press, which created unnecessary anxiety among the thousands of patients who have already received stents. Since the data supporting the main meta-analysis that created this concern proved to be not scientifically sound, the lack of a more balanced data presentation and critical review, which could have prevented needless discomfort and suffering, was regretted. The ECS also stated, however, that the positive side of the debate was that existing randomized trials and registries were intensely scrutinized, resulting in plans for more adequately powered trials with results applicable to the majority of patients treated for coronary artery disease.

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European Society of Cardiology