Management of high defibrillation threshold

The implantable cardioverter defibrillator (ICD) has become the primary therapy for the treatment of potentially lethal ventricular arrhythmias. Ventricular arrhythmias encompass a spectrum of rhythm disturbances ranging from the occasional monomorphic ventricular premature complex to the almost universally fatal ventricular fibrillation. Our understanding of the mechanisms of ventricular fibrillation and defibrillation is still in evolution. At present, the most common ICD configuration consists of a pectoral pulse generator (active-can) with a bipolar transvenous dual coil lead. A transvenous system with an active-can has improved defibrillation thresholds and the ease of implantation. However, there are various clinical scenarios in which patients with high defibrillation threshold (DFT) are encountered. Although the incidence of high DFT patients is low, it is of significant concern since it may account for sudden cardiac death in patients with ICDs. At present, there are few clinical trials that are rigorous and well designed, and which can define a perfect methodology for the treatment of high DFT patients. In this review, in the context of commonly encountered clinical scenarios, we discuss therapeutic strategies to help manage patients with high DFT.