ESC: One in Four Emergency Angioplasty Procedures Linked to Stent Thrombosis

VIENNA, Sept. 7 -- Stent thrombosis after acute myocardial infarction accounts for about 4% of emergency percutaneous coronary interventions, reported investigators here.

Although the overall rate of stent thrombosis is estimate at 1% to 2%, at centers that do coronary interventions, this is not a rare event, said Francesco Burzotta, M.D. of the Catholic University of the Sacred Heart in Rome, at the European Society of Cardiology meeting here.

Dr. Burzotta said data from the OPTIMIST (Outcome of PCI for Stent Thrombosis Multicenter Study) series of 110 patients with stent thrombosis indicated that 3.6% of emergency percutaneous coronary interventions for acute MI are related to the device complication.

Additionally, he said this large series confirmed again what has been widely reported, that stent thrombosis bare metal stents occurs early -- usually in fewer than 30 days -- and late with drug-eluting stents.

But regardless of stent type the prognosis -- even with state of the art treatment -- was poor, 17% mortality and 29% rate of major coronary or cerebral events.

Sixty-two thromboses occurred in drug-eluting stents and 52 involved bare metal stents (some patients had more than one stent thrombosis), he said.

The study included 110 patients treated for stent thrombosis at 11 hospitals in the greater Rome area during 2005 and 2006. Clinical and procedural data were recorded using a detailed questionnaire and clinical outcomes were tracked for six months are intervention.

Dr. Burzotta and colleagues also compared the efficacy of thrombectomy to re-stenting to establish optimal blood flow. An independent core laboratory analyzed optimal coronary blood flow data.

Mechanical removal of the thrombus with specifically designed thrombectomy devices was used in one of every four patients, but it did not significantly improve outcome, he said. But when the devices were used in relatively stable patients -- those without cardiogenic shock -- "there was a five-fold improved rate of optimal coronary flow restoration."

Moreover, "despite the fact that patients treated by thrombectomy were sicker than the others, no excess of adverse clinical events was observed," he said.

That observation suggests "the role of distal embolization and its prevention may be important only before advanced heart damage has been established," he said.

Among the findings:

• Drug-eluting stent thrombosis was more likely to occur more than 30 days after implantation or 15 days after withdrawal of dual antiplatelet therapy.
• Clinical manifestation of stent thrombosis was not influenced by stent type, i.e. drug-eluting versus base metal stent.
• Mortality was higher when stent thrombosis occurred a year or more after implantation.

Dr. Burzotta said that when stent thrombosis was treated by implanting additional stents the percutaneous coronary interventions result was not optimal. "This suggests that the goal should establishment of optimal coronary blood flow rather than attempting to reduce residual coronary vessel stenosis by further stenting."

He concluded, "percutaneous coronary interventions for stent thrombosis is not a rare type of emergency procedure in the hospitals performing coronary interventions" and predicted that the number of cases "is likely to increase as use of stents continues to increase."