Antiplatelet pretreatment effects in patients with non-ST-segment elevation acute coronary syndromes in a center without daily 24 hours access to the catheter laboratory

BACKGROUND: Pretreatment in patients with non-ST elevation acute coronary syndrome (NSTE-ACS) is controversial. OBJECTIVES: Evaluate the safety and efficacy of pretreatment in a center without daily access to the catheter laboratory (CL). METHODS: This prospective observational single-center study (June 2021-June 2024) included patients with suspected NSTE-ACS undergoing coronary angiography (CAG). Clinical, biochemical and CL data were registered. Patients were monitored during their hospital stay for bleedings events (BE), ischemic events (IE) and misdiagnosis. RESULTS: 443 consecutive patients with suspected NSTE-ACS were included. Median age was 70.0 years (IQR 60.0-77.0) and 71.8 % were male. 84.0 % were under pretreatment. IE, BE and cardiovascular death were of 5.0 %, 4.1 % and 1.8 %, respectively. IE were more frequent in the non-pretreatment group (10.3 % vs 4.1 %; p = 0.030), whereas there was no significant difference in BE (1.4 % vs 4.6 %; p = 0.216). Myocardial infarction (MI) before CAG and type 4b MI rate were lower in the pretreatment group (1.6 % vs 8.5 %; p < 0.001 and 0.3 % vs 2.8 %; p = 0.016, respectively). After adjusting for covariates, pretreatment was associated with a lower incidence of IE (OR 0.35 95 % CI 0.135-0.928; p = 0.035) whereas it was not associated with BE (OR 3.68 95 % CI 0.427-31.651; p = 0.236). A lower estimated glomerular filtration rate and active malignancy were associated with BE, while chronic ischemic heart disease was associated with IE. CONCLUSIONS: Pretreatment was associated with a lower incidence of IE in NSTE-ACS patients with lower rates of MI before CAG and type 4b MI, without a significant increase in BE.