The use of clopidogrel as part of DAPT will be associated with lower bleeding rates compared to ticagrelor in patients with chronic thrombocytopenia requiring Percutaneous intervention (PCI )with Drug Eluting Stent (DES) or Bare Metal Stint(BMS).

Patients with thrombocytopenia are at an increased risk of both bleeding and ischemic events following PCI; however, there is a paucity of data on how to optimally manage these risks. Data indicates that ticagrelor is associated with reduced ischemic outcomes with an accompanying increased risk of bleed in the broader population. This study will assess P2Y12 agent selection in patients with chronic thrombocytopenia to determine if one better balances risks of ischemic and bleeding events following coronary intervention

Inclusion Criteria:

• ≥ 18 years
• PCI with either DES or BMS during study time period (April 1, 2018 through July 1 2021)
• Thrombocytopenia defined as platelet count <100 x103 /µL on at least one occasion prior to PCI
• At least one dose of DAPT post-PCI with aspirin and either clopidogrel or ticagrelor

Exclusion Criteria:

• Death within 48 hours post-PCI
• DAPT prior to cardiac catheterization

Study population of 18 years of age ,PCI with either DES or BMS during study time period (April 1, 2018 through July 1 2021) ,Thrombocytopenia on at least one occasion prior to PCI and at least one dose of DAPT post-PCI with aspirin and either clopidogrel or ticagrelor