Session P73.8

A Novel Heart Rate Variability Index for Evaluation of Left Ventricular Function Using Five-Minute ECGs

S Babaeizadeh*, S Zhou, X Liu, W Hu, D Feild,
E Helfenbein, R Gregg, J Lindauer

Philips Medical Systems
Thousand Oaks, CA, USA

Introduction: Based on the frequency-domain analysis of Heart Rate Variability (HRV), we calculated the VHF (Very High Frequency) component and VHF Index (VHFI), and tested on patients with known reduced left ventricular function. We found that VHFI has the potential to be a useful tool for quick evaluation of left ventricular function.
Study population: Patients (n=177) who were admitted to Ruijin Hospital due to Coronary Heart Disease (CHD) were randomly selected for the study. The study group (n=76) consisted of post-MI or dilated cardiopathy patients with decreased left ventricular systolic function (LVEF=40.5±7.1%, 21~49.5%). The control group (n = 101) consisted of patients with normal heart function by echocardiogram (LVEF=68.0±4.2%, 55~76%) and without severe coronary artery stenosis (<30%) by coronary angiography. Hypertension and diabetes mellitus were not excluded.
Methods: Five-minute 12-lead ECGs at 500sps were recorded using a Philips PageWriter Touch electrocardiograph (which has five-minute ECG storage), and annotated using the Philips Holter analysis program (2010W). Heart rate power was estimated using Lomb-Scargle periodogram method. The main spectral components, VLF, LF, and HF (Very Low, Low, and High Frequencies), which have been extensively studied for short term ECG analysis, were not useful in our study. We defined a new index VHFI as the VHF component of the spectra normalized to represent its relative value in proportion to the total power minus the VLF component.
Results: VHFI is a continuous index and its limit can be set at any level depending on the population. We defined the positive test as VHFI=14 and negative test as VHFI<10 and obtained a sensitivity of 71.9% with a specificity of 81.7% with 17.5% unclassified. More precisely, in the study group 46 patients had VHFI=14 and 18 had VHFI<10 and 12 had 14>VHFI=10 when in the control group 67 patients had VHFI<10 and 15 had VHFI=14 and 19 had 14>VHFI=10.
Conclusions: The lower specificity can be explained by inclusion of hypertension and diabetes mellitus patients in the control group. We believe the new index VHFI has potential for fast assessment of severe LV dysfunction. Calculating this index needs only 5 minutes of ECG which can be recorded easily in any environment. We plan to further enhance the algorithm efficiency by combining VHFI with other ECG analysis indices.

(Abstract Control Number: 41)