Baseline thrombocytopenia in acute coronary syndrome: The lower, the worse.

BACKGROUND Patients with baseline thrombocytopenia can increase mortality and morbidity in patients with studying acute coronary syndromes (ACS), but are typically excluded from randomized clinical trials studying ACS. We sought to better define the effect thrombocytopenia on clinical outcomes in ACS patients. METHODS Patients identified from the NCDR Chest Pain registry at Mayo Clinic Arizona from Oct 2015 to Sep 2018 were retrospectively classified into two groups: TP (platelet <150 × 103 μL) and control (platelet ≥150 × 103 μL). The groups were analyzed for the clinical outcome (all-cause mortality, major adverse cardiac events (MACE), and bleeding events). The TP group was divided into moderate-severe thrombocytopenia (TPmod; platelet 50-100 × 103 μL) and mild thrombocytopenia (TPmild; platelet 100-150 × 103 μL) for further analysis. P-value <0.05 is considered significant. RESULTS Five hundred and thirty-six patients were identified, and 72 patients (13%) had thrombocytopenia. The median follow-up time was 1.1 years. The TP group was older (TP vs. control: mean age 73 ± 13 years vs. 70 ± 13 years; P = 0.026). In patients discharged on dual-antiplatelet therapy, the TP group had higher all-cause mortality (23% vs. 7.3%; P = 0.007) but not major bleeding events (11% vs. 5.0%; P = 0.123). Only all-cause mortality increased with the severity of thrombocytopenia (TPmod vs. TPmild vs. control: 33% vs. 24% vs. 7.3%; P = 0.007). CONCLUSIONS In patients with ACS, baseline thrombocytopenia is associated with increased all-cause mortality and all bleeding events without net MACE benefit. Further study is needed to identify the optimal antiplatelet strategy in this higher risk population.