Perspective:

The current manuscript concerns a novel extravascular ICD, which is being considered for regulatory approval. Currently available ICDs are either the transvenous or totally subcutaneous devices. A totally subcutaneous ICD avoids the vascular and mechanical complications of a transvenous device, but due to its totally subcutaneous location, it cannot do antitachycardia pacing. It also has shorter battery longevity and larger size, both of which are the consequences of the extrathoracic location of the lead and the generator. The substernal location of the novel ICD described in this manuscript provides the benefit of a lower energy requirement for shocks and painless therapy with antitachycardia pacing. The inappropriate shock rate was mostly due to atrial oversensing, and the authors indicate they modified their approach during the study to reduce this risk. The novel extravascular ICD shows a promise of the best of two worlds, but it will require implanting cardiologists to learn how to safely and reliably enter a space heretofore off limits to them.