Design: Prospective, global, single-arm post-approval registry
Population: 787 patients with an attempted extravascular ICD implant
Primary outcome: Freedom from major system- or procedure-related complications at 1 year
Effect: 89.1% (95% CI 86.3–91.3%); inappropriate shock 7.1%

The Enlighten post-approval registry followed 787 patients worldwide in whom 168 operators attempted implantation of an extravascular ICD, which places the lead substernally rather than inside the heart. Mean age was 49 and about a third were implanted for secondary prevention.

Substernal lead placement succeeded in 99.2%, and 96.3% left with the system in place after testing. At one year, 89.1% (95% CI 86.3–91.3%) were free of major system- or procedure-related complications. Appropriate therapy occurred in 7.3%; all 61 discrete spontaneous shocks terminated the arrhythmia, and antitachycardia pacing succeeded in 74.2% of monomorphic VT episodes. Inappropriate shocks occurred in 7.1%, with non-cardiac oversensing the main cause.

The results match the premarket trials with a broader group of operators. Inappropriate shocks remain the weak point, and this is a single-arm, manufacturer-linked registry with no comparison against transvenous or subcutaneous devices.

The device offers pacing for monomorphic VT without an intravascular lead, unlike the subcutaneous ICD.
Warn patients that about 1 in 14 had an inappropriate shock in the first year.
Consider it for younger patients in whom avoiding transvenous lead complications matters most.
It does not provide bradycardia pacing for patients who need it long term.

Why it matters

It widens the choice for patients who need antitachycardia pacing but would be better without a lead in the heart.

The statistics, in plain English

Kaplan–Meier estimates give the proportion event-free at one year allowing for people followed for different lengths of time. Without a comparison group, these figures describe the device but cannot show it is better or worse than alternatives.