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November 2016

Clinical Outcomes of Patients Who Received the Subcutaneous Implantable Cardioverter Defibrillator

Author Affiliations
  • 1Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts
JAMA Cardiol. 2016;1(8):965. doi:10.1001/jamacardio.2016.2877

The implantable cardioverter defibrillator (ICD) has emerged as the dominant clinical strategy for the prevention of sudden cardiac death (SCD) on the basis of improved survival in multiple, appropriately designed prospective randomized clinical trials.1 Primary prevention clinical trials provide consistent and conclusive evidence that the ICD reduces overall mortality among selected patients at risk for SCD with left ventricular dysfunction due to dilated nonischemic cardiomyopathy or ischemic heart disease.1 For patients with prior sustained ventricular arrhythmias, the ICD has emerged as the best approach for prolonging survival in secondary prevention trials.1 When indicated for primary and secondary prevention, the use of the ICD is beneficial and cost-effective. This evidence of clinical benefit has been demonstrated exclusively with conventional ICD systems with transvenous leads.1 These leads, which are used for pacing, sensing, and high-voltage shocks for cardioversion or defibrillation, have many limitations, including implantation-related vascular, cardiac, and pulmonary complications. Endovascular infection commonly mandates lead extraction, which is associated with considerable risk. Other disadvantages are transvenous lead–related proarrhythmia and tricuspid regurgitation. Furthermore, lead failures have occurred at an unacceptably high rate. They can result in delivery of inappropriate shocks, with the accompanying psychological trauma, or they can impede appropriate therapy. Although strong evidence supports improved survival among selected patients with conventional transvenous ICD systems, the lead remains a notable weakness. Based on well-publicized lead-performance issues, transvenous-ICD leads can be appropriately considered the Achilles’ heel of traditional ICD systems.2

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