Stent Thrombosis

Stent thrombosis is defined as a thrombotic occlusion of a coronary stent. Stent thrombosis is a major complication associated with stent placement in percutaneous coronary intervention (PCI). Stent thrombosis has been associated with high rates of morbidity and mortality, often leading to events of cardiac death or nonfatal myocardial infarction (MI). Often compared to in-stent restenosis, which leads to anginal type symptoms, stent thrombosis is typically an acute process resulting in acute coronary syndrome (ACS). Various risk factors have been associated with stent thrombosis, including a history of diabetes mellitus (DM), ACS, and reduced left ventricular ejection fraction (LVEF). In 2008, the Academic Research Consortium (ARC) guidelines were published regarding the classifications of stent thrombosis. Classifications were divided based on the type of underlying stent, clinical scenario, and timing after initial stent placement.

1. Based on the underlying stent, stent thrombosis should be divided into categories of a bare-metal stent (BMS), a first-generation drug-eluting stent (DES), and second-generation DES.

In terms of timing, there are a variety of categories for stent thrombosis. Timing may be divided between acute, subacute, early, late, and very late. Early stent thrombosis is divided between acute or subacute:

1. Acute thrombosis occurs within 24 hours of initial placement.

2. Subacute thrombosis occurs between 24 hours to one month of initial placement.

When classified as early, late, or very late:

1. Early stent thrombosis occurs within one month of initial placement.

2. Late stent thrombosis occurs between 1 and 12 months of initial placement.

3. Very late stent thrombosis occurs after 12 months of initial placement.

Based on the clinical scenario, stent thrombosis may be symptomatic or clinically silent. As noted above, due to the nature of acute thrombotic occlusion stent thrombosis typically results in ACS. Stent thrombus should be classified based on how the diagnosis is confirmed. These classifications include definite, probable, and possible stent thrombosis.

1. Silent occlusion- Incidental stent occlusion on angiography in the absence of clinical signs or symptoms is not considered stent thrombosis.

1. Possible stent thrombosis

   1. Consider with unexplained death 30 days or later after stent placement.

1. Probable stent thrombosis

   1. Any unexplained death within 30 days of stent placement.

   2. Consider if there is active ischemia on electrocardiogram (EKG) or stress in the distribution of prior stent and absence of significant coronary lesion on angiography.

1. Definite stent thrombosis

   1. Requires confirmation of stent thrombosis on angiography

      1. Within the existing stent

      2. Within 5 mm proximal or distal to the stent

2. 1. Plus one of the following within 48 hours

      1. Acute onset of ischemic symptoms at rest

      2. New ischemic changes on ECG

      3. A typical rise in cardiac biomarkers

      4. Thrombus on autopsy or retrieved with thrombectomy