This is a prospective, 1:1 randomized, interventional, multicenter and international trial. Approximately 790 subjects are expected to be enrolled to 40 sites in the south of Europe and Middle East.

The objective of this study is to evaluate and compare the efficacy of the first appropriate shock of an ICD in a ventricular tachyarrhythmia, when the waveform of the shock is programmed with the standard waveform, Fixed Tilt with a value of 65% (Control Group), versus the exclusive waveform programmable in SJM ICDs, Fixed Pulse Width (Study Group), in a standard population of subjects with ICD indication.

Inclusion Criteria:

• Subjects who meet the current ESC indications for ICD or CRT-D implant. This includes upgrades indications from pacemaker to ICD or to CRT-D or replacements of ICDs or CRT-Ds provided that there is no previous record of ineffective shocks

  • Subjects who are willing to be registered on the Merlin.net remote follow-up program
  • Subject ≥18 years
  • Subjects with life expectancy of at least 1 year
  • Subjects who agree to comply with the follow-up program included in this protocol

Exclusion Criteria:

• • Subjects on the waiting list for a heart transplant or under consideration for a transplant over the next 12 months

  • Subjects with Myocardial infarction or unstable angina within 40 days prior to enrollment
  • Subjects who have undergone a recent cardiac revascularization (PTCA, Stent or CABG) procedure in the 4 weeks prior to enrollment
  • Functional NYHA Class IV
  • Subjects who are participating in another ICD or CRT-D study
  • Subjects who are pregnant at the time of enrollment or women of childbearing potential that do not take contraceptives
  • Any disability or limitations to correctly understand or complete the study (physical, intellectual, logistical)