The subcutaneous implantable cardioverter-defibrillator cannot achieve adequate arrhythmia sensing for all patients, and elec- trocardiographic screening to assess sensing is required prior to implantation.S11.1-10,S11.1-11 Some advocate exer- cise testing after device implantation to ensure proper sensing with exercise. Both transvenous and subcutaneous implantable cardioverter-defibrillators have SVT-VT discriminators that can be programmed to facilitate discrimination of SVT from VT; however, these discriminators do not always work. If sustained VT is confirmed, therapy to terminate the arrhythmia is delivered. All ICDs provide shocks to terminate VT or VF, but shocks in an awake patient are painful and associated with decreased QoL. Transvenous ICDs are capable of bradycardia pacing as well as antitachycardia pacing that can terminate many VTs painlessly. Subcutaneous implantable cardioverter- defibrillators provide limited postshock bradycardia pacing but do not provide either bradycardia or antit- achycardia pacing. The subcutaneous implantable cardioverter-defibril- lator recommendations supplant, but do not nullify, the need for waiting periods and other requirements to be satisfied for ICD/CRT implantation specified in other parts of this document. Recommendation-Specific Supportive Text 1. The subcutaneous implantable cardioverter- defibrillator was designed to avoid the need for venous access and some of the complications of inserting transvenous lead(s)S11.1-1 S11.1-4 that include pneumothorax, hemothorax, and cardiac Difficulties in achieving venous access can prolong the implantation procedure and occasionally result in failed ICD implantation. These difficulties are more likely to be encoun- tered in patients with limited venous access such as patients with ESRD. 