title: How many patients fulfil the surface electrocardiogram criteria for subcutaneous implantable cardioverter-defibrillator implantation?
abstract: OBJECTIVE
  To determine the number of patients with a primary or secondary prevention implantable cardioverter-defibrillator (ICD) indication who are eligible for subcutaneous ICD (S-ICD) implantation according to the S-ICD manufacturer's surface electrocardiogram (ECG) screening template.
  
  
  RESULTS
  One hundred and ninety-six ICD patients with a non-paced ventricle were assessed using erect and supine ECG limb lead recordings to simulate the three S-ICD sensing vectors. Each ECG lead was scrutinized by two independent observers. Subcutaneous ICD eligibility required two or more leads to satisfy the S-ICD screening template in both erect and supine positions. Overall, 85.2% of patients [95% confidence interval (CI): 80.2-90.2%] fulfilled surface ECG screening criteria. The proportion of patients with 3, 2, 1, and 0 qualifying leads were 37.2% (95% CI: 30.4-44.0%), 48.0% (95% CI: 41.0-55.0%), 11.2% (95% CI: 6.8-15.6%), and 3.6% (95% CI: 1.0-6.2%). The S-ICD screening template was satisfied more often by Lead III (primary vector, 83.7%, 95% CI: 78.5-88.9%) and Lead II (secondary vector, 82.7%, 95% CI: 77.4-88.0%) compared with Lead I (alternate vector, 52.6%, 95% CI: 45.6-59.6%). A prolonged QRS duration was the only baseline characteristic independently associated with ineligibility for S-ICD implantation. There was 92.9% agreement between the two independent observers in assessment of eligibility using the S-ICD screening template.
  
  
  CONCLUSIONS
  About 85.2% of patients with an indication for a primary or secondary prevention ICD have a surface ECG that is suitable for S-ICD implantation when assessed with an S-ICD screening template. There is minor inter-observer variation in assessment of eligibility using the S-ICD screening template.
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool, L14 3PE, UK.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Randles
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool, L14 3PE, UK.
authors.forename: Nathaniel M
authors.initials: NM
authors.lastname: Hawkins
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool, L14 3PE, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Shaw
authors.affiliation: Department of Cardiology, University Hospital of North Staffordshire, Stoke on Trent, ST4 7LN, UK.
authors.forename: Ashish Y
authors.initials: AY
authors.lastname: Patwala
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool, L14 3PE, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Pettit
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool, L14 3PE, UK David.Wright@lhch.nhs.uk.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wright
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000295:instrumentation*; D004562:Electrocardiography; D004608:Eligibility Determination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D018579:Patient Selection; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011322:Primary Prevention / Q000295:instrumentation* / Q000379:methods; D019919:Prosthesis Implantation / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D055502:Secondary Prevention / Q000295:instrumentation* / Q000379:methods
keywords: Electrocardiogram; Subcutaneous implantable cardioverter-defibrillator