Journal of Clinical and Diagnostic Research. 2023 Jan, Vol-17(1): LE01-LE04 1 1 DOI: 10.7860/JCDR/2023/57454.17270 Nursing Section Predictors of Heart Rate Variability: A Systematic Review Review Article RANI JOSE 1 , NEETHA KAMATH 2 , SREEJA GOPALAKRISHNAPILLAI 3 , SALINA SUNIL 4 ABSTRACT Introduction: The heart has the ability to maintain cardiac output in accordance with the body’s momentarily changing demands by adjusting its rate of contractions and this ability is termed Heart Rate Variability (HRV), which is manifested as a fluctuation of R-R interval in milliseconds on an Electrocardiography (ECG). Maintenance of good HRV levels is significant for the patient population since they influence the prognosis and quality of life. Aim: To identify the predictors of HRV. Materials and Methods: The present study was a systematic and literature review which was based on Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines 2020. Randomised Controlled Trials (RCTs) published in English from 2014 to 2021 were identified from Cochrane Library, Science Direct, PubMed, and Google Scholar databases. The keywords with Boolean operators were used as “influencing factors or determinants or predictors and HRV.” The quality assessments of the studies were performed with Cochrane risk-of-bias assessment tool. Narrative syntheses upon the selected studies were done. Results: The significant findings from the nine selected RCTs were summarised. Physical exercise, breathing exercise, diet, music, and mind-body interventions such as yoga and meditation were identified as the factors enhancing HRV or predictors of HRV. Conclusion: The findings of this systematic review strive to facilitate healthcare providers to devise the strategies to support the risk group of low HRV by the implementation of enhancing factors of HRV to achieve a better outcome. INTRODUCTION The heart is a unique organ with a capacity to maintain cardiac output in accordance with the body’s momentarily changing demands by adjusting its rate of contractions. This ability is termed HRV, manifested as a fluctuation of R-R interval in milliseconds on an ECG. A person with high HRV can be considered healthy in terms of physical, social, mental, and spiritual aspects. Measurement and maintenance of good HRV levels are significant for the patient population since they influence the prognosis and quality of life [1]. The heart rate is modulated by a balance between the sympathetic and parasympathetic systems. The neuro-cardiac function reflects the interaction between the heart and brain, measured by the HRV. Hence, researchers and clinicians worldwide use HRV to measure the heart’s autonomic control [2]. HRV is an emerging concept in the field of medical treatment, and the available empirical data on the factors affecting HRV are scattered. Many factors can influence HRV. Several studies were conducted to identify, the influence of individual factors on HRV. According to a review, physiological, pathological, neuropsychological, lifestyle, and environmental factors can influence HRV [3]. The studies involving a compilation of the factors which can enhance HRV may facilitate the healthcare providers to devise strategies to support the risk group of low HRV. The enhancement of HRV is directly related to Parasympathetic Nervous System (PNS) activation [4]. This systematic review addresses the research question, that what are the factors enhancing HRV. The main objective was to identify the positive predictors of HRV. MATERIALS AND METHODS Search Strategy The review followed the guidelines of PRISMA 2020 [5]. The Prospero Id for the review was registered as CRD42021270016. The steps for conducting the systematic review comprised locating the sources, selecting the studies, and quality appraisal of studies, followed by the presentation of findings. A systematic review of literature for articles in the English language, published from 2014 to 2021, was conducted using electronic databases such as Cochrane Library, Science Direct, PubMed, and Google Scholar. The keywords used for the search were “influencing factors”, “HRV” combined with Boolean operators “AND” and “OR” with the synonyms “determinants” and “predictors”. In addition to the above, a reference list of all relevant articles and reviews was checked. Inclusion criteria • Typeofstudy-RCTspublishedbetween2014-2021 • Language-English • Studyparticipants-Adultsofbothgenderagedabove18years • Full-textarticleavailability. Exclusion criteria Articles on- • Paediatricpopulation, • Pregnantandlactatingmothers. After identifying the records through databases and reference lists, duplicates were removed manually. Two levels of screening were completed independently by three authors, the first level was the screening of title and abstracts, and the second level was the full-text screening of eligible studies. Disagreements concerning article inclusion were resolved within the group discussion. Three reviewers worked independently to reduce the chance of error, add more scrutiny, and ensure proper conduct. The literature search in various databases and reference list of other relevantarticlesyielded360studies.Afterexcluding15duplicates, there were 345 articles, of which 288 articles that were not relevant based on the selection criteria were excluded, and the remaining 57 records were identified for screening. Another 44 studies were also eliminated as they had multiple outcome measures other than factors influencing HRV. A risk-of-bias assessment screening was done for the remaining 13 records, and four studies were eliminated. Ultimately, nine studies were considered for data synthesis. The studyselectionprocessisdepictedinPRISMA[Table/Fig-1][5]. Keywords: Determinants,Exercises,Infuencingfactors