Table 2:
Characteristics of the Included Studies
| Study | Number of Participants | Study Design | Center(s) Involved, Country | Data Source (Sample Dates) | Indication(s) for WCD | Age: Mean ± SD (Median) | Male Sex | Baseline EF: Mean ± SD (Median) | WCD Use: Mean ± SD (Median) | Compliance: Mean ± SD (Median, 25%–75% Range) | Premature Discontinuation* | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wäßnig et al.5 | 6,043 | R | Multicenter, Germany | Zoll database† (April 2010–October 2013) | • | DCM (37%) | (57 years) | 79% | NR | (59 days) | (23.1, 21.0–23.7) | NR |
| • | ICM with CAD and low EF‡ (27%) | |||||||||||
| • | NICM (12%) | |||||||||||
| • | Explanted ICD (12%) | |||||||||||
| • | Myocarditis (10%) | |||||||||||
| • | Genetic disease (1%) | |||||||||||
| • | Heart transplant candidate (0.7%) | |||||||||||
| • | Heart failure (0.5%) | |||||||||||
| Kutyifa et al.6 | 2,000 | P | Multicenter, US | WEARIT-II Registry (August 2011–February 2014) | • | NICM (46%) | (62 years) | 70% | (25%) | (90 days) | (22.5, 2.69 IQR) | NR |
| • | ICM with previous MI or known CAD (40%) | |||||||||||
| • | Congenital/inherited heart disease (13%) | |||||||||||
| Bhaskaran et al.11 | 8 | R | Single-center, Australia | Westmead Hospital (November 2013–NR) | • | Explanted ICD due to infection (38%) | NR | NR | 36% ± 18% (28%) | 100 ± 78 days (77 days) | 23.4 ± 0.6 (23.3, 23.0–23.7) | NR |
| • | DCM (25%) | |||||||||||
| • | Aortic stenosis (13%) | |||||||||||
| • | Myocarditis (13%) | |||||||||||
| • | Post-partum cardiomyopathy (13%) | |||||||||||
| Kondo et al.12,¶ | 24 | R | Single-center, Germany | University Hospital of Bonn (August 2010–November 2014) | • | Early post-MI for primary prevention (46%) | 69 ± 12 years | 92% | (30%) | (33 days) | (23.1, 21.6–23.6) | NR |
| • | History of VT/VF (54%) | |||||||||||
| Sasaki et al.13 | 9 | R | Single-center, Japan | Hirosaki University Hospital (April 2014–September 2014) | • | History of VT/VF (89%) | (56 years) | 78% | (35%) | (21 days) | (23.7, 23.6–23.9) | NR |
| • | Early post-MI with reduced EF (11%) | |||||||||||
| Epstein et al.14 | 8,453 | R | Multicenter, US | Zoll database (September 2005–July 2011) | • | Early post-MI (100%)# | 63 ± 13 years | 73% | NR | 69 ± 61 days (57 days) | (21.8, NR) | NR |
| Saltzberg et al.15,¶,|| (a) | 107 | R | Multicenter, US | Zoll database (2003–June 2009) | • | Pregnancy-related cardiomyopathy (100%)# | 31 ± 6 years | 0% | 22% ± 9% | 124 ± 123 days (87 days) | 18.3 ± 5.3 (20.4, NR) | 14% |
| Saltzberg et al.15,¶,|| (b) | 159 | R | Multicenter, US | Zoll database (2003–June 2009) | • | Nonischemic or idiopathic DCM** with no mention of pregnancy-induced cause (100%) | 33 ± 7 years | 0% | 21% ± 8% | 96 ± 83 days (76 days) | 17.0 ± 6.2 (19.3, NR) | 8% |
| Rao et al.16,|| (a) | 119 | R | Multicenter, US | Zoll database (2005–2010) | • | Inherited arrhythmias (100%) | 38 ± 13 years | 45% | 57% ± 10% | (29 days) | (19, 10–22) | 9% |
| Rao et al.16,|| (b) | 43 | R | Multicenter, US | Zoll database (2005–2010) | • | Congenital structural heart disease (100%) | 37 ± 12 years | 47% | 37% ± 19% | (27 days) | (19, 12–21) | 9% |
| Chung et al.17,¶¶ | 2,274 | R | Multicenter, US | Zoll database (August 2002–December 2006) | • | Explanted ICD (28%) | 59 ± 15 years | 74% | NR | 52.6 ± 69.9 days (36 days) | 19.9 ± 4.7 (21.7, NR) | 14% |
| • | Recent NICM with EF ≤ 35% (24%) | |||||||||||
| • | History of VT/VF (19%) | |||||||||||
| • | Post-CABG with EF ≤ 35% (11%) | |||||||||||
| • | Unspecified cardiomyopathy with EF ≤ 35% (10%) | |||||||||||
| • | Miscellaneous or unknown (8%) | |||||||||||
| Klein et al.18 | 354 | R | Single-center, Germany | University Hospital in Magdeburg (January 2000–June 2008) | • | Complicated§§ early post-MI (39%) | 58 ± NR years | 82% | NR | 106 ± NR days | 21.3 ± NR | 4% |
| • | Complicated*** post-CABG (25%) | |||||||||||
| • | Myocarditis/DCM (10%) | |||||||||||
| • | Explanted ICD due to infection (10%) | |||||||||||
| • | Heart transplant candidate (6%) | |||||||||||
| • | Syncope of unknown origin/aborted SCA (5%) | |||||||||||
| • | Long QT/Brugada syndrome (3%) | |||||||||||
| • | Delay/refusal of ICD implantation (2%) | |||||||||||
| Feldman et al.19 | 289 | P | Multicenter, US, and single-center, Germany | WEARIT and BIROAD studies (NR) | • | NYHA class III/IV HF with EF < 30% (61%, WEARIT population) | 55 ± 12 years | 82% | 23% ± 10% | 93 ± NR days | NR | 24% |
| • | Complicated††† early post-MI or post-CABG; ICD candidate not expected to receive the device for at least four months; or ICD implantation refusal (39%, BIROAD population) | |||||||||||
BIROAD: Bridge to ICD in Patients at Risk of Arrhythmic Death; CABG: coronary artery bypass graft; CAD: coronary artery disease; DCM: dilated cardiomyopathy; EF: ejection fraction; ICD: implantable cardioverter-defibrillator; ICM: ischemic cardiomyopathy; MI: myocardial infarction; NICM: nonischemic cardiomyopathy; NR: not reported; P: prospective; R: retrospective; SCA: sudden cardiac arrest; SD: standard deviation; US: United States; VF: ventricular fibrillation; VT: ventricular tachycardia; WCD: wearable cardioverter-defibrillator; WEARIT: Wearable Defibrillator Investigative Trial; WIF: Wearable Defibrillator Use in Heart Failure; NR: not reported.
*Due to comfort issues, nonadherence, adverse reactions.
†German national database maintained by Zoll; all other Zoll databases in table used US data.
‡Including patients post-MI within 40 days and post-revascularization within 90 days.
||Patients included if early post-MI with an EF ≤ 35% or had a diagnosis code for acute MI (ICD-9 code: 410.xx).
#Results only reported for specific cohorts separately.
**Patients included if they had a diagnosis code for cardiomyopathy (ICD-9 codes: 425.4, 425.8); peri-partum cardiomyopathy (ICD-9 codes: 674.5, 674.45, 674.8); or secondary cardiomyopathy (ICD-9 code: 425.9) coupled with a reference to current or recent pregnancy (six or less months since last pregnancy).
¶Results only reported for specific cohorts separately.
¶¶Patients included if they had a diagnosis code for cardiomyopathy (ICD-9 codes: 425.4, 425.8) or secondary cardiomyopathy (ICD-9 code: 425.9).
§§Baseline demographics from entire study population.
***Pre- or early postoperative poor ventricular function, prolonged and difficult postoperative hemodynamic recovery, or early post-operative life-threatening ventricular tachyarrhythmias.
†††Ventricular tachyarrhythmia within 48 hours of the event, EF < 30% at least three days after the event, or an episode of syncope or sudden cardiac arrest at least 48 hours after the event but without candidacy for an ICD.