**5.1 Transient contraindication for an ICD**

One of the main reasons for WCD use is ICD system infection, which poses a clinical challenge in that the best course of action is to extract the device and lead(s), submit the patient to a course of antibiotic therapy, and then replace the ICD system with a new device [7, 9, 45]. The rate of infections associated with cardiac implantable electronic systems continues to increase, even at high-volume centers [46]. Antimicrobial therapy may last 10–14 days or longer, depending on the nature of the infection and the patient's response. During this time, the patient is without an ICD. Leaving the ICD in place while treating an infection is associated with a high mortality rate (31–66%) [47, 48], but removing the device also increases the patient's mortality rate, albeit from 8–27% [49–51]. Thus, the clinician faces three challenges: if the device is replaced too early, the patient risks re-infection; if the patient is deprived of the device too long, there is a risk for potentially life-threatening arrhythmias; and placing the patient under close monitoring in the hospital or a long-term care facility is cost prohibitive and deleterious to the patient's quality of life. In such cases, the use of a WCD can be a valuable interim solution for arrhythmic rescue.

In a study of 97 ICD patients whose devices had to be explanted for infection, patients were prescribed a WCD for the mean antimicrobial treatment course of 21 days. As they recovered from infection, two patients experienced a total of four VT episodes, all of which could be successfully treated [52]. In a retrospective analysis of 8058 patients who received a WCD from 2002 to 2014 when an infected ICD was removed, 4% experienced ventricular tachyarrhythmias, and the rate of arrhythmic episodes was greatest in the first 3 weeks after device explantation (0.9, 0.7, and 0.7%, respectively), and the risk for ventricular tachyarrhythmias after device removal was 4% during the first 2 months and 10% at 1 year [25].
