High-residual platelet activity despite the dual antiplatelet treatment with aspirin and clopidogrel is associated with major adverse cardiac events, including stent thrombosis. Acute and subacute stent thrombosis is rare, but presents itself with serious complications including high mortality and morbidity rates. Light transmittance aggregometry with specific agonists - arachidonic acid and 5-adenosin diphosphate - is still considered a standard for the assessment of platelet reactivity, besides novel methods like vasodilator-stimulated phosphoprotein phosphorylation. In our case study, we report the coincidence of high-residual platelet activity with subacute stent thrombosis despite the recommended doses of antiplatelet agents - aspirin and clopidogrel. Stent thrombosis was treated by aspiration thrombectomy, and antiplatelet treatment was modified by increasing the dose of aspirin and substituting clopidogrel with a firstgeneration thienopyridin - ticlopidin. The effect of the treatment was documented by reaching the optimal inhibition of platelet reactivity. In the 6- and 12-month follow-up, the patient presented no ischemic events.