When a clot develops inside a coronary stent, it can block blood flow to the heart, potentially causing a heart attack or even death.
A single incident of stent thrombosis is bad enough, but a new study suggests that one in six patients can expect to experience at least one repeat episode. According to the Dutch Stent Thrombosis Study, among the strongest predictors of recurrent stent thrombosis is implantation of an additional stent during emergency treatment of the first episode.
The study will be reported in a Late-Breaking Clinical Trials session at the SCAI Annual Scientific Sessions in Partnership with ACC i2 Summit (SCAI-ACCi2) in Chicago. SCAI-ACCi2 is a scientific meeting for practicing cardiovascular interventionalists sponsored by the Society for Cardiovascular Angiography and Interventions (SCAI) in partnership with the American College of Cardiology (ACC).
Jochem Wouter van Werkum, MD, a cardiologist at St Antonius Hospital, Nieuwegein, the Netherlands, led the study. He and his colleagues enrolled a total of 437 consecutive patients who had stent thrombosis confirmed by angiography between January 2004 and February 2007. The researchers collected data on clinical characteristics (for example, diabetes, age and duration of antiplatelet therapy), angiographic characteristics (for example, undersizing of the stent, dissection and whether the lesion was located at an arterial branchpoint), and procedural characteristics (for example, whether a drug-eluting or bare-metal stent was used and the length and diameter of the stent).
The researchers found that 74 of the 437 patients (16.9 percent) experienced multiple episodes of stent thrombosis. Of these, 61 patients had two episodes of stent thrombosis, 12 patients had three episodes and one patient had four episodes. Further analysis revealed three independent predictors of repeat stent thrombosis. Patients who had an additional stent implanted during emergency treatment for the first episode of stent thrombosis were 4.2 times as likely as other patients to experience a repeat episode of stent thrombosis (p<0.0001). Patients with a previous heart attack faced 2.6 times the usual risk of repeat stent thrombosis (p<0.001), and patients who developed thrombosis long after stent implantation (late stent thrombosis) faced 2.1 times the usual risk of a repeat episode (p=0.0127).
Dr. van Werkum and his colleagues concluded that additional stent placement at the time of emergency treatment for the first stent thrombosis should be avoided.