Introduction: Small vessel disease (SVD) usually refers to atherosclerosis within vessels of diameter of < 2.5 mm. Conflicting data exist regarding the outcomes of its revascularization.Aim: To evaluate the outcome of invasive treatment in patients with acute coronary syndromes (ACS) and SVD and the predictors of angina recurrence after percutaneous coronary intervention (PCI).Material and methods: This was an observational, retrospective, single-center study. It covered consecutive 127 patients (26.77% women; median age: 69.74 ±8.97 years) with ACS who underwent PCI in the Upper-Silesian Medical Center in Katowice between 2018 and 2020. The study population was stratified by means of presence of SVD defined by PCI of the culprit artery with a diameter of ≤ 2.5 mm. The major adverse cardiac and cerebrovascular events (MACCE) and angina recurrence were analyzed in a 12-month follow-up period.Results: Overall 99 (77.95%) patients were diagnosed with small-vessel coronary artery disease. MACCE were documented in 14 (11.02%) patients. Univariate analysis revealed the following factors associated with MACCE: left ventricle ejection fraction (LVEF) (OR = 0.95, p = 0.0212), left main (LM) stenting (OR = 18.17, p = 0.0216), number of former PCIs (OR = 1.48, p = 0.0235). According to logistic regression analysis the factors were LM stenting (OR = 20.04, p = 0.0216) and number of former PCIs (OR = 1.53, p = 0.0203). Patients with SVD had more often refractory or recurrent angina in symptomatic class III/IV on follow-up (52.53% vs. 10.71%, p < 0.001).Conclusions: Outcome of invasive treatment in patients with ACS is related to LM stenting and former PCIs but not to SVD occurrence. Patients with SVD have a high rate of recurrent/refractory angina despite successful PCI in this clinical setting.