ACS are a potent risk factor for AF, with new onset AF occurring in up to 1 in every 5 patients hospitalized with an ACS.

Despite its relatively frequent occurrence and the many etiologic factors involved in its pathogenetic condition, the frequency and prognostic significance of AF complicating ACS remain unclear

There are limited data available, particularly from a representative population-based perspective describing recent pharmacological and non-pharmacological management and clinical event rates associated with AF complicating ACS in the era of novel treatment strategies (in both AF and ACS) and high coronary reperfusion rates.

This registry will assess the current in-hospital management and clinical events at 6 months of consecutive patients admitted in Italian cardiology intensive care units (CCUs) for an ACS treated invasively with PCI and stent implantation who present AF at admission or during hospital stay, before or after stent implantation .

Inclusion Criteria:

• All consecutive ACS patients treated with PCI with stent implantation who present AF at admission or during hospital stay, before or after stent implantation.

Exclusion Criteria:

• Patients admitted with a diagnosis of ACS at the time of enrolment but not confirmed during hospitalization
• ACS treated medically or with PCI but without stent implantation
• Patients not giving informed consent

Patients with ACS trated with PCI with stent implantation developing or having Atrial Fibrillation.