Response to Letter Regarding Article, “Annual Rate of Transvenous Defibrillation Lead Defects in Cardioverter-Defibrillators Over a Period of >10 Years”
We are thankful to Drs Suri and Keller for their interest in our study.1 Lead defects can have many causes. Therefore, a multilateral approach is needed to reduce the incidence of lead failure. As stated by Drs Suri and Keller, this includes better lead design, improved implantation techniques, and appropriate choice of device.
What is also necessary is a detailed analysis of the better outcome of older leads. This analysis should include lead design, comprising lead diameter and insulation material, and an analysis of the patient’s characteristics. Because the indications for implantable cardioverter-defibrillators have been extended in the last few years, the number of younger more active patients with longer life expectancy is increasing continuously. Newer lead models have to overcome the growing demands that these patients place on them. Lead testing standards that correspond better to real life are warranted before a new lead model is introduced.
As correctly pointed out by Drs Suri and Keller, routine implantable cardioverter-defibrillator controls failed to identify nearly one third of lead defects, and lead failure was detected only by the presence of inappropriate shocks. Early detection before clinical presentation with inappropriate shocks or sudden death is important. Routine defibrillation threshold testing, looking for shock impedance and postshock oversensing, may allow earlier diagnosis.2 However, it is not clear how many inappropriate shocks would have been prevented by regular defibrillation threshold testing in the present study. In addition, it is not known how often defibrillation threshold testing should be performed. It also should be considered that routine defibrillation threshold testing cannot be performed in all patients because some patients could be at increased risk for stroke resulting from atrial fibrillation and the presence of left atrial thrombus or severe spontaneous echo contrasts.3 Hence, better noninvasive lead surveillance parameters are needed to detect the beginnings of lead failure.