Wavelet Transform Analysis Reveals Differences Between Patients with Impaired Left Ventricular Systolic Function and Healthy Individuals

Background Despite continuous progress in medical treatment, heart failure (HF) is the leading cause of hospitalizations with a high all-cause mortality in patients. Patients with a left ventricular ejection fraction (LVEF) below 50% are characterized by the highest risk of cardiovascular complications. The objective of this study was to examine how LVEF below 50% and aging impact cardiovascular physiology. Methods Sixteen males with physician diagnosed coronary artery disease and LVEF = 42 ± 6% (age 62 ± 6 years, BMI 29.1 ± 3.8kg/m2) and 10 healthy controls (9 male and 1 female, age 28.5 ± 9.1 years, BMI = 24.1 ± 1.2kg/m2) were recruited in our study. Finger photoplethysmography for blood pressure (BP) and electrocardiogram (ECG) were recorded while participants rested in a supine position. Wavelet transformations were used to analyze the amplitudes, phase coherence and phase difference of BP and ECG. The frequency intervals were separated as follows: I (0.6-2Hz), II (0.145– 0.6Hz), III (0.052–0.145Hz), and IV (0.021–0.052Hz). Results HF patients showed a decrease (p<0.05) in BP wavelet amplitude intervals III and IV in comparison to controls, and interval I for ECG. A decrease in phase coherence (p<0.01) at interval I is also found in HF patients compared to controls. Conclusions A decrease in smooth muscle cell activity and smooth muscle autonomic innervation (intervals III and IV) contributions to BP, along with a decrease in cardiac activity as shown by the wavelet amplitude in ECG, suggests altered BP and ECG function in aging HF patients. Furthermore, a decrease in the cardiac interval represents an impairment in the BP and ECG relationship in HF patients. The wavelet transform has the potential to expand our understanding of LVEF and improve diagnostic procedures and patient prognosis. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work has been partially supported by subsidy Funds of Electronics, Telecommunications and Informatics Faculty, Gdansk University of Technology. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was conducted in accordance with the Helsinki recommendations and was approved by the Ethics Committee of Medical University of Gdansk (NKBBN/864/2022-2023). The Ethics Committee of University of Regina (REB#2017-013) approved this study and the experimental protocol. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy. The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.