title: Increased amount of interstitial fibrosis predicts ventricular arrhythmias, and is associated with reduced myocardial septal function in patients with obstructive hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  Reduced echocardiographic strain is associated with ventricular arrhythmias in hypertrophic cardiomyopathy (HCM) patients. The aim of this cross-sectional study was to investigate which type of histological fibrosis contributes to ventricular arrhythmias and reduced septal longitudinal strain, in obstructive HCM-patients with or without additional coronary artery disease (CAD) and/or hypertension (HT).
  
  
  RESULTS
  Sixty-three HCM-patients (mean age 57 ± 13 years) were included. Strain by speckle tracking echocardiography was performed prior to either percutaneous transluminal septal ablation (n = 37) or septal myectomy (n = 26). In 24 patients myectomy specimens were available (histology population) and allowed determination of %area of interstitial and replacement fibrosis. Twenty-nine (46%) patients had concomitant CAD and/or HT, and 15 (24%) experienced ventricular arrhythmias defined as documented ventricular tachycardia or arrhythmogenic suspected syncope. The patients with ventricular arrhythmias had lower septal longitudinal strain compared with those without arrhythmias (-9.0 ± 4.0 vs. -13.6 ± 5.6%, P = 0.006). In the histology population reduced septal longitudinal strain correlated to interstitial (R(2) = 0.36 P = 0.003), but not to replacement fibrosis (R(2) = 0.03 P = 0.43). By logistic regression analyses, interstitial fibrosis predicted ventricular arrhythmias (OR 1.16, 95% CI 1.02-1.32, P = 0.03), while replacement fibrosis did not (OR 1.22, 95% CI 0.93-1.59, P = 0.15).
  
  
  CONCLUSIONS
  Total amount of fibrosis was a marker of ventricular arrhythmias in obstructive HCM-patients. Interstitial fibrosis seemed to be more important compared with replacement fibrosis in arrhythmogenesis, and was related to reduced septal myocardial function. These findings suggest that interstitial fibrosis may play an important role as the arrhythmogenic substrate, and that strain echocardiography can help detection of patients at risk.
authors: Department of Cardiology, Oslo University Hospital, Rikshospitalet, PO Box 4950, Nydalen, N-0424 Oslo, Norway. vibeke.marie.almaas@ous-hf.no
authors: Vibeke M
authors: VM
authors: Almaas
authors: Kristina H
authors: KH
authors: Haugaa
authors: Erik H
authors: EH
authors: Strøm
authors: Helge
authors: H
authors: Scott
authors: Christen P
authors: CP
authors: Dahl
authors: Trond P
authors: TP
authors: Leren
authors: Odd R
authors: OR
authors: Geiran
authors: Knut
authors: K
authors: Endresen
authors: Thor
authors: T
authors: Edvardsen
authors: Svend
authors: S
authors: Aakhus
authors: Jan Peder
authors: JP
authors: Amlie
mesh_terms: D000328:Adult; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000000981:diagnostic imaging*; D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D004719:Endomyocardial Fibrosis / Q000150:complications* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014693:Ventricular Fibrillation / Q000150:complications* / Q000000981:diagnostic imaging*
keywords: Echocardiography; Hypertrophic cardiomyopathy; Myocardial fibrosis; Ventricular arrhythmias