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. 2010 Jul 13;56(3):194-203.
doi: 10.1016/j.jacc.2010.04.016.

Aggregate national experience with the wearable cardioverter-defibrillator: event rates, compliance, and survival

Mina K Chung  1 , Steven J Szymkiewicz, Mingyuan Shao, Edwin Zishiri, Mark J Niebauer, Bruce D Lindsay, Patrick J Tchou
Affiliations

Aggregate national experience with the wearable cardioverter-defibrillator: event rates, compliance, and survival

Mina K Chung et al. J Am Coll Cardiol. .

Abstract

Objectives: The purpose of this study was to determine patient compliance and effectiveness of antiarrhythmic treatment by the wearable cardioverter-defibrillator (WCD).

Background: Effectiveness of the WCD for prevention of sudden death is dependent on event type, patient compliance, and appropriate management of ventricular tachycardia/ventricular fibrillation (VT/VF).

Methods: Compliance and events were recorded in a nationwide registry of post-market release WCDs. Survival, using the Social Security Death Index, was compared with survival in implantable cardioverter-defibrillator (ICD) patients.

Results: Of 3,569 patients wearing the WCD (age 59.3+/-14.7 years, duration 52.6+/-69.9 days), daily use was 19.9+/-4.7 h (>90% of the day) in 52% of patients. More days of use correlated with higher daily use (p<0.001). Eighty sustained VT/VF events occurred in 59 patients (1.7%). First-shock success was 76 of 76 (100%) for unconscious VT/VF and 79 of 80 (99%) for all VT/VF. Eight patients died after successful conversion of unconscious VT/VF (89.5% survival of VT/VF events). Asystole occurred in 23 (17 died), pulseless electrical activity in 2, and respiratory arrest in 1 (3 died), representing 24.5% of sudden cardiac arrests. During WCD use, 3,541 of 3,569 patients (99.2%) survived overall. Survival occurred in 72 of 80 (90%) VT/VF events and 78 of 106 (73.6%) for all events. Long-term mortality was not significantly different from first ICD implant patients but highest among patients with traditional ICD indications.

Conclusions: Compliance was satisfactory with 90% wear time in >50% of patients and low sudden death mortality during use. Survival was comparable to that of ICD patients. However, asystole was an important cause of mortality in sudden cardiac arrest events.

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Figures

Figure 1
Figure 1. Actual WCD Use
A. Duration of Monitoring. Distribution of patients by duration of WCD use. B. Daily hours of use by overall duration of WCD use.
Figure 1
Figure 1. Actual WCD Use
A. Duration of Monitoring. Distribution of patients by duration of WCD use. B. Daily hours of use by overall duration of WCD use.
Figure2
Figure2. Events while wearing the WCD
ECG=electrocardiogram, PM=pacemaker. VT/VF = ventricular tachycardia/ventricular fibrillation, WCD = wearable cardioverter defibrillator,
Figure 3
Figure 3. Short- and Long-term Kaplan-Meier Survival Analyses of WCD patients by Traditional vs. Non-Traditional ICD Indications
A. 3-month cumulative mortality. B. Long-term cumulative mortality.
Figure 3
Figure 3. Short- and Long-term Kaplan-Meier Survival Analyses of WCD patients by Traditional vs. Non-Traditional ICD Indications
A. 3-month cumulative mortality. B. Long-term cumulative mortality.
Figure 4
Figure 4. Kaplan-Meier Survival Analyses of WCD patients by Specific ICD Indications
A. Short term (3-month). B. Long term (3-year). Traditional ICD indications include cardiomyopathy with LVEF ≤35%, ICD explant awaiting reimplantation, and ventricular tachycardia/ventricular fibrillation (VT/VF) awaiting ICD implantation, and genetic predisposition to sudden cardiac death (SCD). Non-traditional indications include recent MI with LVEF >35%, post-CABG with LVEF ≤35%, recent MI with ≤35, recently diagnosed cardiomyopathy (CM) with LVEF ≤35%.
Figure 4
Figure 4. Kaplan-Meier Survival Analyses of WCD patients by Specific ICD Indications
A. Short term (3-month). B. Long term (3-year). Traditional ICD indications include cardiomyopathy with LVEF ≤35%, ICD explant awaiting reimplantation, and ventricular tachycardia/ventricular fibrillation (VT/VF) awaiting ICD implantation, and genetic predisposition to sudden cardiac death (SCD). Non-traditional indications include recent MI with LVEF >35%, post-CABG with LVEF ≤35%, recent MI with ≤35, recently diagnosed cardiomyopathy (CM) with LVEF ≤35%.
Figure 5
Figure 5. Short- and long-term Kaplan-Meier survival analysis of WCD and ICD patients
A. 3-month cumulative mortality. B. 3-year cumulative mortality. ICD=implantable cardioverter defibrillator. WCD = wearable cardioverter defibrillator.
Figure 5
Figure 5. Short- and long-term Kaplan-Meier survival analysis of WCD and ICD patients
A. 3-month cumulative mortality. B. 3-year cumulative mortality. ICD=implantable cardioverter defibrillator. WCD = wearable cardioverter defibrillator.
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