title: Ventricular Tachyarrhythmias in Patients With Hypertrophic Cardiomyopathy and Defibrillators: Triggers, Treatment, and Implications.
abstract: BACKGROUND
  Triggers and ICD interventions of ventricular arrhythmias in patients with hypertrophic cardiomyopathy (HCM) offer insight into mechanisms and treatment.
  
  
  RESULTS
  Intracardiac ICD electrograms from 71 HCM patients in the HCM I and II studies were analyzed by three individuals. Rhythms were defined as VF (polymorphic ventricular arrhythmia), VT (monomorphic ventricular tachycardia), and ventricular flutter (VFL; VT ≥ 240 bpm). Physical activity and rhythm preceding the arrhythmia were ascertained. Of 149 arrhythmias, VF was present in 74, VT in 57, and VFL in 18. In those whose activity was known, moderate or intense physical activity was associated with over 50% of the tachycardias (57 of 111). Rhythms preceding ventricular arrhythmias were often sinus tachycardia (49 of 149; 33%) or rapid atrial fibrillation (7 of 149; 5%). VF and VFL were more likely preceded by supraventricular rhythms >100 bpm (30 of 68 with VF; 44%; 12 of 16 with VFL 75%, vs. 14 of 50 with VT 28%; P = 0.001). Antitachycardia pacing (ATP) was successful in 39 of 53 (74%). Multiple shocks were more often required to terminate VFL (10 of 18; 56%) compared to VF (10 of 72; 14%) and VT (2 of 25; 8%; P < 0.0001). Of arrhythmias requiring more than one shock to terminate, 16 of 22 were preceded by sinus tachycardia and/or moderate or extreme physical activity.
  
  
  CONCLUSIONS
  Rapid supraventricular rhythms, and at least moderate activity, frequently precede VT and VF, and when they occur in these situations often require multiple ICD shocks to restore sinus rhythm. ATP is successful in terminating VT and VFL, and should be a programmed in all HCM patients with ICDs.
authors.affiliation: UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Link
authors.affiliation: Mount Sinai Medical Center, New York, New York, USA.
authors.forename: Katy
authors.initials: K
authors.lastname: Bockstall
authors.affiliation: Tufts University Medical Center, Boston, MA, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Weinstock
authors.affiliation: College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates.
authors.forename: Alawi A
authors.initials: AA
authors.lastname: Alsheikh-Ali
authors.affiliation: Centenary Institute, University of Sydney, and Royal Prince Alfred Hospital, Sydney, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Semsarian
authors.affiliation: Tufts University Medical Center, Boston, MA, USA.
authors.forename: N A Mark
authors.initials: NAM
authors.lastname: Estes
authors.affiliation: Policlinico di Monza, Monza, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Spirito
authors.affiliation: Minneapolis Heart Institute Foundation, Minneapolis, Minnesota, USA.
authors.forename: Tammy S
authors.initials: TS
authors.lastname: Haas
authors.affiliation: Tufts University Medical Center, Boston, MA, USA.
authors.forename: Ethan J
authors.initials: EJ
authors.lastname: Rowin
authors.affiliation: Tufts University Medical Center, Boston, MA, USA.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Maron
authors.affiliation: Tufts University Medical Center, Boston, MA, USA.
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Maron
mesh_terms: D000200:Action Potentials; D000293:Adolescent; D000328:Adult; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000175:diagnosis; D002648:Child; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000295:instrumentation*; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy*; D055815:Young Adult
keywords: antitachycardia pacing; athletes; atrial fibrillation; exercise; hypertrophic cardiomyopathy; implantable cardioverter defibrillators; ventricular fibtillation; ventricular tachycardia