Stent thrombosis incidence in bare metal stents


 * Associate Editors-In-Chief: Smita Kohli, M.D.; Varun Kumar, M.B.B.S.; Lakshmi Gopalakrishnan, M.B.B.S.

Overview

 * Multiple contemporary studies involving single center and multi center experience suggests an overall lifetime incidence of stent thrombosis is 0.5 % - 2.5 %.


 * There is some variation of these numbers with the definitions used. For instance, in a recent study of 8847 patients who received a BMS, a cumulative incidence of definite, probable or possible stent thrombosis (ST) over 15 months was 2.15% and that for definite ST was 0.61%.


 * In a study involving serial angiography after sirolimus-eluting stent (SES) and BMS implantation at 4, 11, and 21.2 ± 2.2 months, no BMS developed thrombus, however SES demonstrated the presence of thrombi and yellow plaques even as much as 2 years after implantation.

Incidence of early ST in BMS
For purposes of discussion this group would include:
 * Intra-procedural ST
 * Acute ST: up to 24 hrs
 * Subacute ST: 24 hrs to 30 days

Supportive trial data:
 * In study of 7484 patients with (intra vascular ultrasound study) IVUS before and after stenting, incidence of ST was 0.4% up to a week. The median time of ST was 24 hours and the minimum time was 1 hour.


 * In a retrospective analysis 4509 patients the rate of subacute ST was 0.51%.

Higher incidence of subacute ST in special patient populations:


 * In a group of 40 patients who underwent non cardiac surgery following BMS, the incidence of ST while on two antiplatelet agents appeared to be 2.5 % (one patient out of 40).


 * Incidence of ST in patients with acute coronary syndrome(ACS) are higher than those with stable angina as demonstrated by ACUITY and TRITON-TIMI 38 trial databases.


 * The incident rates of early ST in ACS i.e STEMI and NSTEMI have shown to be 1.4 - 1.6%, and 0 - 2.9% respectively while ST incidence in patients with stable angina is 0 - 0.5%.

Incidence of ST from 30 days up to 3 years or longer
This would include:
 * Late ST: 30 days to one year
 * Very late ST: more than one year, but generally less than 3 years
 * Later than 3 years

The reported incidence in this group ranges between 0-0.5%. Given the paucity of data only assumptions can be made for the group beyond 1-3 years.

Incidence of late-ST:


 * The incidence of late ST with BMS was 0.28% in a meta-analysis of 14 trials looking at 6675 patients.


 * Long term aspirin therapy is necessary to reduce the incidence of late ST in patients with BMS.


 * Late ST is uncommon in patients who are on dual anti-platelet therapy(DAT).


 * With the use of second generation BMS, and current antithrombotic regimens (aspirin and thienopyridine) the 30 days ST incidence range from 0.5-2.5% in high risk patients. The incidence is higher if aspirin is used alone or when warfarin is used along with aspirin without thienopyridine.

Incidence of very late-ST:


 * It appears that ST in the very late group is exceedingly rare.


 * In a meta-analysis of 14 trials looking at 6675 patients no patient presented with very late ST of BMS. However regular follow up of most patients confined to one year or less.