The role of the Wearable Cardiac Defibrillator (WCD) in protecting ischemic cardiomyopathy (ICM) and nonischemic cardiomyopathy (NICM) patients at risk for sudden cardiac arrest (SCA) who are not immediate candidates for the implantable cardiac defibrillator (ICD)

Abstract

Background There are >30,000 deaths in the United States annually due to sudden cardiac death (SCD). SCD from a ventricular tachyarrhythmia (VT) is a significant contributor to mortality in patients with heart disease. If defibrillation therapy is delivered within minutes of the patient's collapse, this renders the highest probability of surviving life-threatening VT. The WCD is a temporary, non-surgical device, designed for patients who are at risk for SCA but are not appropriate candidates for ICD implantation at the present time. The WCD allows providers time to assess their long-term arrhythmic risk and make appropriate plans for those patients at a perceived risk, who may show clinical improvement after being medically optimized. Post-MI patients with heart failure are at 4–6 times greater risk of SCA in the first 30 days post-MI. The rate of sustained ventricular tachyarrhythmia (SVT) by three months was 3% among patients with ICM and in congenital/inherited heart disease, and 1% among NICM patients. The WEARIT-II registry demonstrated a high rate of SVT at three months in at risk patients who were not eligible for an ICD, suggesting that wearing the WCD can be safely used to protect patients during this period of risk assessment. Methods Between October 1, 2015 and September 30, 2017, the patients who used the WCD were included in this retrospective chart review. All patients with ICM and NICM that met the criteria for WCD were included. The number of subjects in the database determined the sample size pragmatically over a two-year period of time. Data was entered into an Excel spreadsheet for Windows. Descriptive statistics were conducted to describe the sample demographics. Frequency and percentages were calculated for nominal data and means were calculated for continuous data. Conclusion Patients who are at risk for SCA are patients who have had a cardiac arrest due to ventricular fibrillation (VF) or sustained ventricular tachycardia (SVT), those with familial or inherited condition with sudden cardiac arrest risk, myocardial infarction with an ejection fraction (EF) of less than or equal to 35%, dilated cardiomyopathy (including NICM), with an EF of less than or equal to 35%, ICD explanations, and other conditions with high risk of ventricular tachycardia (VT) or VF are candidates for the WCD. The sample of data was from 186 patients. However, more patients were likely candidates but may not have been considered due to lack of awareness or provider preference of the WCD. Of those patients, four received a living saving shock from the WCD. Two were ICM and two were NICM. Of the sample population, there was a much smaller group of woman than men protected with the WCD. Recognizing at risk patients for SCA can be challenging. There is considerable controversy regarding the use of the WCD in the short term for cardiomyopathy patients. The use of the WCD has shown to be lifesaving in both the ICM and NICM patients in protecting them from SCA. However, the risk assessment among patients with NICM is less straightforward that's for patients with ICM. The WCD is a therapeutic option, listed along with implantable cardioverter defibrillators (ICDs), in the ACC/AHA/ESC Guidelines for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. It is also a Class I recommendation in the International Society for Heart and Lung Transplantation Guidelines for the Care of Cardiac Transplant Candidates. Result The PinnacleHealth CardioVascular Institute enrolled 186 patients with ischemic (N= 60, 32.3%), and nonischemic (n= 126, 67.7 %) cardiomyopathies prescribed the WCD between October 1, 2015 through September 30 2017. Clinical data, arrhythmic events, and ejection fractions were captured. The median age was 62-years-old; there were 58 female patients (31%) and 128 male patients (69%), the median ejection fraction was 25%. Four patients received appropriate WCD shock. Two patients were NICM (2%) and two patients were ICM (4%). Of the two ICM there was one VT and one VF arrest. Of the NICM they were both shocked for VF arrests.