1. Wearable Cardioverter Defibrillators
2016
Wearable Cardioverter Defibrillators
Susan O’Donoghue, M.D.
Presenter:

2. Approved Indications for Implantable Cardioverter-Defibrillator (ICD)
Secondary prevention: post VT/VF no acute MI or other reversible cause Primary Prevention: CAD with prior MI>40 days EF<35% if Class ll or lll EF<30% if Class l CAD pt must be 3 months post CABG or PCI NICM EF<35% must have 3 mos GDMT Familial or inherited condition with high risk VF (channelopathies; HCM)

3. Indications for ICD Implantation
ICD placement NOT indicated within 40 days AMI or within 3 months post revascularization or new diagnosis NICM because benefit has not been demonstrated in clinical trials, and a significant number of patients have improvement in EF

4. defibrillation electrodes
WCD 3000 LifeVest System
Self-gelling
defibrillation electrodes
No adhesive, no gel ECG
Response buttons
Stores ECG, daily use, etc.
1.8 lbs
150 joules

5. Wearable Cardioverter-Defibrillator (WCD) Therapy
4-electrode 2 lead system
Programmable VT and VF zones
If arrhythmia detected alert tones and vibration allow patient to abort shock
If patient does not abort, gel deployed; shock strength up to 150 J, up to 5 shocks
Shock efficacy 69-99%

6. WCD Clinical Experience
Observational studies reported, none randomized
Variety of patient populations and durations of therapy
Incidence of appropriate shocks %
Incidence of inappropriate shock %

7. WCD Clinical Experience in Patients with Newly Diagnosed Cardiomyopathy
There is one study in USA reporting WCD data specifically in patients in the “waiting period” after new Dx of low EF
Retrospective review of all patients prescribed WCD from at University of Pittsburg
254 pts with newly Dx NICM and 271 with newly Dx ICM – average time WCD use 66 days

8. From: Utility of the Wearable Cardioverter-Defibrillator in Patients With Newly Diagnosed Cardiomyopathy: A Decade-Long Single-Center Experience

9. Conclusions – WCD in Newly Diagnosed Cardiomyopathy
In NICM short term risk is minimal (0/254 pts received an appropriate shock)– routine use of WCD in this group should be prospectively evaluated
In ICM 4/271 pts (1.5%) survived a WCD shock and received an ICD - all therapies occurred in males with QRS > 120 msec
Lifevest cost during the study $2.2 million

10. German Observational Study of WCD Use
Diagnosis Patients Frequency of WCD shocks Total cohort 6, (%) DCM 2,220 (36.7) 1.3 ICM 1,629 (26.9) 1.4 NICM 735 (12.2) 1.0 ICD explant 717 (11.9) 3.2 Myocarditis 595 (9.8) 1.3 Genetic Disease 80 (1.4) 2.3 HTx 40 (0.7) 2.5 CHF 25 (0.4) 4.0 Circulation August 2016
December 5, 2017

11. WCD Cost and Cost Efficacy
Lifevest rental approx. $3,300/month
2015 cost analysis using $2,700/month estimated cost <$100,000/quality-adjusted life year gained as long as the event rate was at least 1.7% per month
J Innov Card Rhythm Management 2015

12. Applying Classification of Recommendations and Level of Evidence
Class I Benefit >>> Risk
Procedure/ Treatment SHOULD be performed/ administered
Class IIa Benefit >> Risk Additional studies with focused objectives needed
IT IS REASONABLE to perform procedure/administer treatment
Class IIb Benefit ≥ Risk Additional studies with broad objectives needed; Additional registry data would be helpful
Procedure/Treatment
MAY BE CONSIDERED
Class III
Risk ≥ Benefit No additional studies needed
Procedure/Treatment should NOT be performed/administered SINCE IT IS NOT HELPFUL AND MAY BE HARMFUL
Level of Evidence:
Level A: Data derived from multiple randomized clinical trials or meta-analyses
Multiple populations evaluated;
Level B: Data derived from a single randomized trial or nonrandomized studies Limited populations evaluated
Level C: Only consensus of experts opinion, case studies, or standard of care
Very limited populations evaluated

13. AHA Science Advisory on WCD Use
WCD use is reasonable when there is an existing indication for ICD but therapy must be delayed (eg. for infection) (llA –level of evidence C)
Circulation April 2016

14. AHA Science Advisory on WCD Use
WCD use may be reaonable when there is concern about heightened risk that may resolve eg newly Dx ICM or NICM (llB-level of evidence C)
Caveat : “Blanket use of WCD in this way not appropriate or consistent with clinical evidence, but may be useful in certain patients with high risk features”
Circulation April 2016

15. WCD Contraindications (Class lll)
Nonarrhythmic risk > arrhythmic risk
Life expectancy < 6 months
Patient unable to understand device function or unable to respond to alerts to abort inappropriate shock

16. WCD – Ongoing Clinical Trials
VEST – randomizing pts within 7 days post MI
SWIFT – observational study evaluating 4 groups: advanced HF, newly Dx CM (ischemic or nonischemic), AMI with Killip class lll-lV, and pts awaiting ICD reimplant
No randomized studies of new NICM alone are likely because of large number needed given low risk

17. Medstar Electrophysiologists’ Consensus Recommendations for WCD
Use WCD for those with existing ICD indication when there is need to delay
Patients in the 40 day ICM or 3 month NICM waiting period should be informed of the data (1.5% risk for ICM, no demonstrated risk for NICM) and the discussion/decision documented – WCD not routinely recommended
In patients with high risk features (eg ICM with QRS>120, large AMI with NSVT ) WCD may be recommended based on physician judgement
Patients presenting with syncope need EP evaluation