© 2005 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.
Heart rate turbulence and left ventricular ejection fraction in Chagas disease
aCardiologia, Dipartimento di Medicina, Chirurgia e Odontoiatria, Ospedale San Paolo, Università di Milano, via A. di Rudinì 8 20142 Milan, Italy; bHospital das Clínicas and Post-Graduation Course in Tropical Medicine, School of Medicine, Universidade Federal de Minas Gerais Belo Horizonte, Brazil; cKlinikum rechts der Isar, Munich University of Technology Munich, Germany; dMACSIN, Laboratório de Modelagem, Análise e Controle de Sistemas Não-Lineares, Universidade Federal de Minas Gerais, Belo Horizonte MG, Brazil
AIMS: Chagas disease patients often present premature ventricular complexes (PVCs), depression of left ventricular ejection fraction (LVEF) and autonomic dysfunction, which is generally evaluated by heart rate variability (HRV) analysis. As frequent PVCs may complicate HRV computation, we measured heart rate turbulence (HRT) and evaluated the correlation between ejection fraction and HRT or HRV in Chagas disease.
METHODS: We studied 30 patients (47 ± 11 years, 20 men) with Chagas cardiomyopathy and left ventricular dilatation who underwent clinical evaluation, ejection fraction (EF: 45 ± 14%) determination and 24-h Holter monitoring (median PVC = 1781). In all patients, the standard deviation of normal RR intervals (SDNN), the square root of the mean square differences of successive RR intervals (RMSSD) and values of turbulence onset (TO) and turbulence slope (TS) were calculated.
RESULTS: HRT indices were independent of mean RR interval and presented high correlation with EF: TO (–0.11 ± 0.01%, r = –0.60, P < 0.001) and TS (5.8 ± 3.7 ms/RR-interval, r = 0.73, P < 0.001). Of HRV parameters, only SDNN, corrected for mean RR interval, showed a weak but not significant correlation with EF (r = 0.41). The comparison of HRT/EF and HRV/EF correlation coefficients, indicated the presence of a significant difference (P = 0.017).
CONCLUSIONS: HRT indices appear to correlate better with EF than SDNN in Chagas disease. Thus, an analysis based on heart rate transient adaptation seems to perform better than HRV in detecting the autonomic alterations that parallel left ventricular dysfunction in Chagas disease patients. The high number of PVCs observed in these patients further support the use of HRT methodology.
Key Words: Chagas disease, heart rate variability, heart rate turbulence, left ventricular dysfunction, vagal control, autonomic nervous system
*Corresponding author. Tel./fax: +39 02 50323145. E-mail address: federico.lombardi{at}unimi.it (F. Lombardi).
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  A. Bauer, M. Malik, G. Schmidt, P. Barthel, H. Bonnemeier, I. Cygankiewicz, P. Guzik, F. Lombardi, A. Muller, A. Oto, et al. Heart Rate Turbulence: Standards of Measurement, Physiological Interpretation, and Clinical Use: International Society for Holter and Noninvasive Electrophysiology Consensus J. Am. Coll. Cardiol., October 21, 2008; 52(17): 1353 - 1365. [Abstract] [Full Text] [PDF]
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