title: Exercise-induced ventricular arrhythmias and risk of sudden cardiac death in patients with hypertrophic cardiomyopathy.
abstract: BACKGROUND
  Non-sustained ventricular tachycardia (NSVT) during ambulatory electrocardiographic monitoring (typically occurring at rest or during sleep) is associated with an increased risk of sudden cardiac death in patients with hypertrophic cardiomyopathy. The prevalence and prognostic significance of ventricular arrhythmias during exercise is unknown.
  
  
  RESULTS
  This was a cohort study, with prospective data collection. We studied 1380 patients, referred to a cardiomyopathy clinic in London, UK [mean age 42 years (SD 15); 62% male; mean follow-up 54 (SD 49) months]. Patients underwent two-dimensional and Doppler echocardiography, upright exercise testing, and Holter monitoring. Twenty-seven patients [mean age 40 (SD 14) years (18-64); 22 (81.5%) male] had NSVT (24) or ventricular fibrillation (VF) (3) during exercise. During exercise, 13 (54.2%) had more than one run of NSVT (maximum 5) with a mean heart rate of 221 (SD 48) b.p.m. Patients with exercise NSVT/VF had more severe hypertrophy (22.6 vs. 19.5 mm, P = 0.009) and larger left atria (47.3 vs. 43.7 mm, P = 0.03). Male gender was significantly associated with exercise NSVT/VF [22 (81.5%) vs. 832 (61.5%), P = 0.03]. Eight (29.6%) of the exercise NSVT/VF patients died or had a cardiac event (SD/ICD discharge/transplant) compared with 150 (11.1%) patients without exercise NSVT/VF, P = 0.008. Patients with NSVT/VF had a 3.73-fold increase in risk of SD/ICD discharge (HR 95% CI: 1.61-8.63, P = 0.002). Exercise NSVT alone was associated with a 2.82-fold increased risk (HR 95% CI: 1.02-7.75, P = 0.049). In multivariable analysis with other risk markers, exercise NSVT/VF (but not NSVT alone) was independently associated with an increased risk of SD/ICD [HR 3.14 (95% CI: 1.29-7.61, P = 0.01)].
  
  
  CONCLUSIONS
  Ventricular arrhythmia during symptom limited exercise is rare in patients with hypertrophic cardiomyopathy, but is associated with an increased risk of sudden cardiac death.
authors.affiliation: The Heart Hospital, University College London, 16-18 Westmoreland Street, London W1G 8PH, UK.
authors.forename: Juan R
authors.initials: JR
authors.lastname: Gimeno
authors.forename: Maite
authors.initials: M
authors.lastname: Tomé-Esteban
authors.forename: Carla
authors.initials: C
authors.lastname: Lofiego
authors.forename: José
authors.initials: J
authors.lastname: Hurtado
authors.forename: Antonios
authors.initials: A
authors.lastname: Pantazis
authors.forename: Bryan
authors.initials: B
authors.lastname: Mist
authors.forename: Pier
authors.initials: P
authors.lastname: Lambiase
authors.forename: William J
authors.initials: WJ
authors.lastname: McKenna
authors.forename: Perry M
authors.initials: PM
authors.lastname: Elliott
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000401:mortality; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000401:mortality; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D015716:Electrocardiography, Ambulatory; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000209:etiology; D016027:Heart Transplantation / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D055815:Young Adult