6. Major periprocedural complications (death, stent thrombosis, vessel perforation, arrhythmias requiring cardioversion, temporary pacemaker insertion or intravenous antiarrhythmic agents, respiratory failure requiring intubation, vascular injury (pseudoaneurysm, arteriovenous shunt, retroperitoneal bleeding or hematoma >5 cm at the arterial catheter insertion site), major bleeding (need for bood transfusion or drop in haemoglobin post-PCI by ≥ 5 gr/ dl or intracranial bleeding).