title: Clinical Risk Stratification for Primary Prevention Implantable Cardioverter Defibrillators.
abstract: BACKGROUND
  A conceptualized model may be useful for understanding risk stratification of primary prevention implantable cardioverter defibrillators considering the competing risks of appropriate implantable cardioverter defibrillator shock versus mortality.
  
  
  RESULTS
  In a prospective, multicenter, population-based cohort with left ventricular ejection fraction ≤35% referred for primary prevention implantable cardioverter defibrillator, we developed dual risk stratification models to determine the competing risks of appropriate defibrillator shock versus mortality using a Fine-Gray subdistribution hazard model. Among 7020 patients referred, 3445 underwent defibrillator implant (79.7% men, median, 66 years [25th, 75th: 58-73]). During 5918 person-years of follow-up, appropriate shock occurred in 204 patients (3.6 shocks/100 person-years) and 292 died (4.9 deaths/100 person-years). Competing risk predictors of appropriate shock included nonsustained ventricular tachycardia, atrial fibrillation, serum creatinine concentration, digoxin or amiodarone use, and QRS duration near 130-ms peak. One-year cumulative incidence of appropriate shock was 0.9% in the lowest risk category, and 1.7%, 2.5%, 4.9%, and 9.3% in low, intermediate, high, and highest risk groups, respectively. Hazard ratios for appropriate shock ranged from 4.04 to 7.79 in the highest 3 deciles (all P≤0.001 versus lowest risk). Cumulative incidence of 1-year death was 0.6%, 1.9%, 3.3%, 6.2%, and 17.7% in lowest, low, intermediate, high, and highest risk groups, respectively. Mortality hazard ratios ranged from 11.48 to 36.22 in the highest 3 deciles (all P<0.001 versus lowest risk).
  
  
  CONCLUSIONS
  Simultaneous estimation of risks of appropriate shock and mortality can be performed using clinical variables, providing a potential framework for identification of patients who are unlikely to benefit from prophylactic implantable cardioverter defibrillator.
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.). dlee@ices.on.ca.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Lee
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Judy
authors.initials: J
authors.lastname: Hardy
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Healey
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: David
authors.initials: D
authors.lastname: Birnie
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Simpson
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Eugene
authors.initials: E
authors.lastname: Crystal
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Iqwal
authors.initials: I
authors.lastname: Mangat
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Kumaraswamy
authors.initials: K
authors.lastname: Nanthakumar
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Xuesong
authors.initials: X
authors.lastname: Wang
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krahn
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Paul
authors.initials: P
authors.lastname: Dorian
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.affiliation: From the Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.S.L., J.H., X.W., P.C.A., J.V.T.); Peter Munk Cardiac Centre (D.S.L., K.N.) and Joint Department of Medical Imaging (D.S.L.), University Health Network (D.S.L., K.N.), Institute for Health Policy, Management and Evaluation (D.S.L., P.C.A., J.V.T.), Division of Cardiology, Department of Medicine, Sunnybrook Health Sciences Centre (E.C., J.V.T.), and Division of Cardiology, Department of Medicine, St. Michael's Hospital (I.M., P.D.), University of Toronto, Toronto, Ontario, Canada; Division of Cardiology, Department of Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada (R.Y.); Division of Cardiology, Department of Medicine, Hamilton Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada (J.S.H.); Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada (D.B.); Kingston General Hospital, Queen's University, Kingston, Ontario, Canada (C.S.S.); and Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
authors.forename: Jack V
authors.initials: JV
authors.lastname: Tu
mesh_terms: D000368:Aged; D002170:Canada / Q000453:epidemiology; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011322:Primary Prevention / Q000379:methods*; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D017180:Tachycardia, Ventricular / Q000401:mortality / Q000628:therapy*
keywords: cardiac arrhythmia; death; decision making; decision support techniques; sudden cardiac death; ventricular fibrillation; ventricular tachycardia