title: Occurrence and frequency of arrhythmias in hypertrophic cardiomyopathy in relation to delayed enhancement on cardiovascular magnetic resonance.
abstract: OBJECTIVE
  Our aim was to determine whether myocardial fibrosis, detected by cardiovascular magnetic resonance (CMR), represents an arrhythmogenic substrate in hypertrophic cardiomyopathy (HCM).
  
  
  BACKGROUND
  Myocardial fibrosis is identified frequently in HCM; however, the clinical significance of this finding is uncertain.
  
  
  METHODS
  We studied prevalence and frequency of tachyarrhythmias on 24-h ambulatory Holter electrocardiogram (ECG) with regard to delayed enhancement (DE) on contrast-enhanced CMR in 177 HCM patients (age 41 +/- 16 yrs; 95% asymptomatic or mildly symptomatic).
  
  
  RESULTS
  Premature ventricular contractions (PVCs), couplets, and nonsustained ventricular tachycardia (NSVT) were more common in patients with DE than those without DE (PVCs: 89% vs. 72%; couplets: 40% vs. 17%; NSVT: 28% vs. 4%; p < 0.0001 to 0.007). Patients with DE also had greater numbers of PVCs (202 +/- 655 vs. 116 +/- 435), couplets (1.9 +/- 5 vs. 1.2 +/- 10), and NSVT runs (0.4 +/- 0.8 vs. 0.06 +/- 0.4) than non-DE patients (all p < 0.0001); DE was an independent predictor of NSVT (relative risk 7.3, 95% confidence interval 2.6 to 20.4; p < 0.0001). However, extent (%) of DE was similar in patients with and without PVCs (8.2% vs. 9.1%; p = 0.93), couplets (8.5% vs. 8.4%; p = 0.99), or NSVT (8.3% vs. 8.5%; p = 0.35).
  
  
  CONCLUSIONS
  In this large HCM cohort with no or only mild symptoms, myocardial fibrosis detected by CMR was associated with greater likelihood and increased frequency of ventricular tachyarrhythmias (including NSVT) on ambulatory Holter ECG. Therefore, contrast-enhanced CMR identifies HCM patients with increased susceptibility to ventricular tachyarrhythmias.
authors.affiliation: Division of Cardiology, Veterans Affairs Medical Center, Minneapolis, Minnesota 55417, USA. adaba001@umn.edu
authors.forename: A Selcuk
authors.initials: AS
authors.lastname: Adabag
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Maron
authors.forename: Evan
authors.initials: E
authors.lastname: Appelbaum
authors.forename: Caitlin J
authors.initials: CJ
authors.lastname: Harrigan
authors.forename: Jacqueline L
authors.initials: JL
authors.lastname: Buros
authors.forename: C Michael
authors.initials: CM
authors.lastname: Gibson
authors.forename: John R
authors.initials: JR
authors.lastname: Lesser
authors.forename: Constance A
authors.initials: CA
authors.lastname: Hanna
authors.forename: James E
authors.initials: JE
authors.lastname: Udelson
authors.forename: Warren J
authors.initials: WJ
authors.lastname: Manning
authors.forename: Martin S
authors.initials: MS
authors.lastname: Maron
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018660:Blood Pressure Monitoring, Ambulatory; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005355:Fibrosis / Q000150:complications / Q000503:physiopathology; D006305:Health Status Indicators; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D018570:Risk Assessment; D013610:Tachycardia / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D013997:Time Factors; D018879:Ventricular Premature Complexes