Purpose. We aimed to analyse the performance of lay responder network and outcome of OHCAs occurred in Swiss Canton Ticino according to the sex of the victim. 
 
 Methods. We performed a retrospective analysis of prospectively collected data of OHCAs since 2005 in Swiss Canton Ticino. When a cardiac arrest is suspected, assisted triage and life support are dispatched and medical assistance is initiated until an ambulance arrives. The Emergency Medical Service dispatcher send the ambulance and, in parallel, notifies the alert to the traditional first-responders (police officers and fire brigade, trained in Basic Life support-Defibrillation and equipped with an Automatic External Defibrillator). If conditions are regarded as safe, the lay responders are notified as well. The latter are mostly lay persons, but even off-duty healthcare providers. 
 
 Results.  A total of 3623 patients, 1140 women (31 %) and 2493 men (69%), were included. OHCA in women occurred more often at home (72% versus 63%, respectively, p<0.001) and less frequently it was witnessed (56% versus 63%, respectively, p <0.001). Women were more likely to be older than men (median age 76 versus 69 years old, respectively, p < 0.001). In the subgroup of patients with a shockable rhythm, no sex differences were observed in cardio-pulmonary resuscitation received by lay responders before ambulance arrival. However, women were less frequently defibrillated by a lay responder (12% versus 22%, p 0.004). 
 
 Conclusions.  In our experience, OHCA presentation and outcome significantly differs according to sex. Women had a lower survival compared to male patients due to different clinical presentation (more often occurring at home and unwitnessed) and to delayed time of defibrillation.

1 - Gender differences in presentation and outcome of out-of-hospital cardiac arrest