title: Prognostic Implications of Defibrillation Threshold Testing in Patients With Hypertrophic Cardiomyopathy.
abstract: In hypertrophic cardiomyopathy (HCM) patients the need for defibrillation threshold (DFT) testing at the time of ICD implantation is debated. Moreover, its prognostic implications have never been explored. In a cohort of HCM patients we sought to (a) investigate factors prompting DFT testing, (b) evaluate ICD efficacy by testing DFT, (c) compare DFT in patients with and without massive LVH, and (d) assess whether DFT testing predicts shock efficacy for spontaneous VT/VF.
  
  
  
  We retrospectively analyzed a cohort of HCM patients implanted with an ICD. DFT was tested at the discretion of the implanting physician with a 10 J safety margin. During follow-up, ICD interventions were evaluated. The study population included 66 patients. DFT was determined in 25 (38%) patients. Age (HR: 0.95; 95%CI: 0.92-0.98; P = 0.004) and massive LVH (HR: 6.0; 95%CI: 2.03-18.8; P = 0.001) affected the decision to test DFT. DFT was at least 10 J less than maximal ICD output in 25/25. Safety margin was similar among patients with and without massive LVH (15 ± 3 J vs. 14 ± 2 J; P = 0.42). During follow-up (median 53 months) 15 shocks were delivered for 12 VT/VF in 7 patients. One VF ended spontaneously after a failed shock. Of 4 unsuccessful shocks, 2 occurred in 1 patient with DFT testing and 2 were delivered in 2 patients without. All unsuccessful shocks were ≤35 J.
  
  
  
  Young age and massive LVH prompt DFT testing. Contemporary ICDs are safe and effective in HCM patients independently from the magnitude of LVH. DFT testing does not predict shock efficacy for spontaneous VT/VF.
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Francia
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.
authors.forename: Carmen
authors.initials: C
authors.lastname: Adduci
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Semprini
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Palano
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.
authors.forename: Daria
authors.initials: D
authors.lastname: Santini
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Musumeci
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Santolamazza
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.|IRCCS Neuromed, Pozzilli (IS), Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Volpe
authors.affiliation: Cardiology, Department of Clinical and Molecular Medicine, St. Andrea Hospital, Sapienza University, Rome, Italy.
authors.forename: Camillo
authors.initials: C
authors.lastname: Autore
mesh_terms: D000328:Adult; D000367:Age Factors; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000295:instrumentation*; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D011237:Predictive Value of Tests; D011475:Prosthesis Failure; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012384:Rome; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D055815:Young Adult
keywords: DFT testing; defibrillation threshold; hypertrophic cardiomyopathy; implantable cardioverter defibrillator; sudden death