Fractal scaling properties of heart rate dynamics and myocardial efficiency in dilated cardiomyopathy.
BACKGROUND
Since altered heart rate (HR) fluctuations provide prognostic information in heart failure, we examined the associations between HR dynamics, myocardial efficiency and perfusion, among patients with dilated cardiomyopathy.


METHODS
Sixteen patients with dilated cardiomyopathy were enrolled. Patients received supervised strength and aerobic training for 5 months (n = 9) or standard care (n = 7). The short-term scaling exponent (alpha(1)) and frequency domain measures of HR behavior were assessed at baseline and after 5 months of intervention. The left ventricular (LV) function measured using echocardiography and oxidative metabolism measured using positron emission tomography (PET) and [(11)C]-acetate were used to estimate the myocardial efficiency.


RESULTS
Short-term fractal exponent alpha(1) correlated significantly with LV myocardial efficiency (r = 0.77, p = 0.002) at baseline. After the intervention period, the majority of patients showed improved myocardial efficiency and small or marked change in HR dynamics toward the natural fractal-like organization (alpha(1) value close 1). Parallel change in fractal properties of HR and myocardial efficiency after intervention was observed in 78% of the patients. Intervention had no significant effect on any other HR fluctuation indices.


CONCLUSIONS
The present study suggests that short-term fractal scaling exponent alpha(1), an important prognostic marker in heart failure, is related to LV myocardial efficiency.
Salo
Tiina Marjatta
TM
Department of Medicine, University of Turku, 20520 Turku, Finland. tiina.salo@tyks.fi
Sundell
Jan
J
Knuuti
Juhani
J
Kemppainen
Jukka
J
Stolen
Kira
K
Nuutila
Pirjo
P
Mäkikallio
Timo H
TH
Huikuri
Heikki V
HV
Airaksinen
K E Juhani
KE
D002311:Cardiomyopathy, Dilated / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D004452:Echocardiography; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D017709:Fractals; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011379:Prognosis; D055070:Resistance Training / Q000379:methods; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*
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