The loss of multifractality as evidence of impaired Left Ventricular Ejection Fraction in patients after acute myocardial infarction

Multifractal analysis of heart rate variability (HRV) has been used to discriminate healthy subjects from patients with severe health conditions. We analyzed the fractal structures of the ECG recording of 11 patients who suffered acute myocardial infarction in order to identify those with impaired Left Ventricular Ejection Fraction (LVEF). Was estimated the multifractal spectrum in Matlab code from the series of RR intervals, in supine rest. The parables representing the multifractal spectrum will be closing in small arcs, as a monofractal structure to 4 these 11 patients. The change in shape of multifractal spectrum curve for this group can provide information on changes in cardiac dynamics of patients with greater impairment of the muscles of the heart. The degree of multifractality, defined as the width of multifractal spectrum, also was studied. Moreover, all patients had undergone Doppler echocardiography and a quantification of left ventricular function was done by the Simpson technique (for LVEF less than 50% the patient was classified as belonging to the group with depressed LVEF). The Mann-Whitney test (p-value <0.01) revealed that the degree of multifractality for the group with impaired LVEF is very significantly lower than for the group with preserved LVEF. We conclude that the loss of multifractality may indicate an impairment of left ventricular ejection fraction in patients after acute myocardial infarction, but we could not measure the extent of this loss as an indication of greater or lesser severity.