title: Fractal correlation properties of R-R interval dynamics in asymptomatic relatives of patients with dilated cardiomyopathy.
abstract: OBJECTIVE
  asymptomatic relatives of patients with familial dilated cardiomyopathy who have left ventricular enlargement [LVE] are at risk for progression to dilated cardiomyopathy. A novel index of the fractal correlation properties of heart rate variability (HRV), the short-term scaling component (proportional, variant(1)) in detrended fluctuation analysis, is a promising prognostic tool in left ventricular dysfunction. The aim of this study was to compare values of proportional, variant(1) and conventional HRV indices in LVE relatives with dilated cardiomyopathy patients and normal controls.
  
  
  METHODS
  time-domain and spectral HRV measures, and the short-term scaling component ( proportional, variant(1)) were assessed from 24-h Holter recordings from 22 LVE relatives (left ventricular end-diastolic dimension >112% predicted, normal fractional shortening), 24 dilated cardiomyopathy patients and 14 controls.
  
  
  RESULTS
  the time domain index SDNN was lower in dilated cardiomyopathy patients [101.8(+/-44.0)] than in LVE relatives [161.7(+/-53.9)] or controls [152.9(+/-51.4)], P=0.01. Similarly, triangular index and spectral measures were reduced in dilated cardiomyopathy patients but not in LVE relatives or controls. In contrast, the short term scaling component ( proportional, variant(1)) in detrended fluctuation analysis was reduced in both dilated cardiomyopathy patients [1.06(+/-0.33)] and in LVE relatives [1.15 (+/-0.20)], compared with controls [1.32(+/-0.16)], P=0.01. Among DCM patients the short-term scaling component ( proportional, variant(1)) was significantly associated with echocardiographic deterioration during follow-up (3.7+/-2.1 year) (P=0.004).
  
  
  CONCLUSIONS
  the short-term scaling component ( proportional, variant(1)) is reduced in asymptomatic relatives of dilated cardiomyopathy patients who have LVE.
authors.affiliation: Department of Cardiological Sciences, St George's Hospital Medical School, London, UK. mahonn@ccf.org
authors.forename: Niall G
authors.initials: NG
authors.lastname: Mahon
authors.forename: Antti E
authors.initials: AE
authors.lastname: Hedman
authors.forename: Mina
authors.initials: M
authors.lastname: Padula
authors.forename: Yi
authors.initials: Y
authors.lastname: Gang
authors.forename: Irina
authors.initials: I
authors.lastname: Savelieva
authors.forename: Johan E P
authors.initials: JE
authors.lastname: Waktare
authors.forename: Marek M
authors.initials: MM
authors.lastname: Malik
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
authors.forename: William J
authors.initials: WJ
authors.lastname: McKenna
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D016022:Case-Control Studies; D018450:Disease Progression; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005192:Family Health; D005260:Female; D005500:Follow-Up Studies; D017709:Fractals; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008131:London / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D013223:Statistics as Topic; D016019:Survival Analysis; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000175:diagnosis / Q000401:mortality