Medical ACLS was initiated in 69 % of the 2690 patients included in the register. ACLS patients were younger (69 years [55–80] vs. 84 years [77–90]) and more frequently men. A higher percentage of witnessed cardiac arrest and BLS were observed. Duration of no-flow was shorter in the ACLS patients, whereas BLS duration was longer. A higher proportion of shockable rhythm and application of AED were found in this group. Mains factors associated with the initiation of medical ACLS were a suspected cardiac cause (1.73 [1.30–2.30]) and use of an automated external defibrillator (1.59 [1.18–2.16]), whereas factors associated with no medical ACLS were higher age (0.93 [0.92–0.94]), absence of BLS (0.62 [0.52–0.73]), asystole (0.31 [0.18–0.51]) and location in nursing home (0.23 [0.11–0.51]).