Outcomes
Outcomes included VA and all-cause mortality. Follow up for outcomes was initiated from the index hospitalization, when ICD/CRTD was implanted, until mortality or last documented visit to HF or device clinic. VA was defined as any VA episode for which an appropriate ATP or shock therapy was delivered by the ICR/CRTD device, as detected during device clinic follow-up. Device clinics were routinely scheduled 1,3 and every 6 months after device implant. During clinic visit, all VA episodes were retrieved from the device and any treatment (ATP, shock or both) was documented. When multiple VAs occurred, the first one was considered for study outcome. Devices were programmed in a ’primary prevention’ mode (similar in all device companies), in accordance with the updated expert consensus on optimal ICD programming (25), consisting of the following detection zones and therapies: VF therapy zone > 200-220 bpm for 24-30 beats, treated via ATP during charge and thereafter device shocks; VT2 therapy zone > 185 bpm for 30 beats or 12 sec duration (BSC devices), treated via ≥1 ATP burst and thereafter device shocks; and a VT1 monitor zone >160 bpm used for monitoring only. Mortality was determined from the Israeli Ministry of the Interior records. The study was approved by the local institutional review board.