Although successful, percutaneous coronary interventions (PCI) with stent implantation may be hampered by periprocedural myocardial necrosis. In acute ST-elevation myocardial infarction (STEMI), the reduction of thrombus burden through manual thrombus aspiration (TA) of an occluded coronary artery has been documented to produce an improved myocardial perfusion rate and significant survival advantage. To date, beyond feasibility and safety studies no clinical benefit has been yet documented with the use of TA before stent deployment in the setting of acute coronary syndromes (ACS) outside acute STEMI. The investigators hypothesize that TA before stent deployment reduces the thrombus/plaque burden - as assessed by intravascular imaging systems - in the setting of acute coronary syndromes (ACS) outside acute STEMI.