Finite-time growth rate to characterize heart rate variability of idiopathic dilated cardiomyopathy patients

A short-term prediction index of heart rate variability (HRV) was applied to a group of 28 patients with idiopathic dilated cardiomyopathy (IDC) and 43 healthy subjects as controls. From IDC group, 22 patients were identified as low-risk of suffering sudden cardiac death (LR_IDC), and 6 patients as high risk group who suffered cardiac death (HR_IDC). From each RR series, 4-h night RR series were selected and divided into segments of 200, 500, 1000, 2000, 5000 and 10000 beats and the finite-time growth rate (FGR) was determined in each segment. A study of the influence of the lag (τ), prediction period (T) and embedding dimension (de) in the calculation of FGR^(de,τ,T) was done. FGR^(3,1,1) calculated from W=1000 beats was able to differentiate IDC (mean±sd: 0.566±0.071) from NRM (mean±sd: 0.633±0.055), p-value≤0.0005. HR_IDC and LR_IDC were statistically differentiated by FGR^(3.1,1) considering W=10000 beats. LR_IDC (mean sd±0.896 ±0.165) and HR_IDC (mean±sd: 0.706±0.118), p-value=0.012.