A Comparative Study on Cardiac Autonomic Dysfunction and Cardiovascular Fitness among Individuals with Prediabetes Prehypertension and with Coexisting Prediabetes and Prehypertension

Abstract

Non-Communicable diseases (NCDs) are the growing causes for morbidity, mortality and economic burden all over the world. Globally, it accounted for 38 million deaths in 2012 and is projected to magnify to 52 million by 2030 (WHO, 2015). Cardiovascular disease (CVD) is the major contributor to NCD related deaths. In India, CVDs cause 24% of all deaths (Sharma, 2013) and it has been predicted that in developing countries the prevalence will increase by almost 75% by 2020 (Gupta, 2005). The leading CVD risk factors include, increased Blood Pressure (BP) (13%), followed by tobacco use (9 %), raised blood glucose (6 %), physical inactivity (6 %) and overweight and obesity (5 %) (WHO, 2011). Hypertension (HTN) and Diabetes mellitus (DM) are interlinked clinical issues that significantly incline the individuals to atherosclerotic CVD, and so commonly known as the bad companions (Epstein, 1997). Analysis of worldwide data for the global burden of HTN indicates that the percentage is projected to increase from 20.6% to 22.9% and 20.9%to 23.6% in men and women of India respectively (Kearney, 2005). According to the International Diabetes Federation (IDF), India ranks second globally with an estimate of 69.2 million adults with DM (IDF, 2015). HTN and DM coexist at a greater frequency than chance alone would predict (Epstein and Sowers, 1992) and the 2 risk of CVD increases by 75% (Sowers et al., 2001), thus indicating that the co-existence in the same individual has a greater negative effect on the cardiovascular (CV) system. newlineThough widespread studies report the altered autonomic activity employing HRV and QT interval in obese subjects, type 2 DM and HTN, reports regarding sympathovagal imbalance in the precursor stages are very sparse. Among the younger age group the prevalence of preDM (17%) (Balagopal et al., 2008), and preHTN (37.45%), (Chitrapu and Thakkallapalli, 2015) is increasing steadily worldwide but the extent and nature of autonomic dysfunction require relatively more attention with special emphasis on individuals reported to have, co-existing preDM and Pre HTN. Till date there has been no, cross-sectional study that has evaluated the autonomic functions using HRV in apparently healthy younger individuals with co-existing PreHTN and PreDM. Thus, we anticipate that this study will give us a better insight about, nature and magnitude of autonomic imbalance occurring in the precursor stages and help to plan earlier interventional strategies. newlineThe present study reports that sympathovagal balance evaluated with the help of HRV and CV fitness assessed using HRR were significantly impaired in individuals reporting co-existing preDM and preHTN compared to subjects with isolated preHTN and preDM. Hereby, we suggest that CV risk factors like BMI, NLR, and arterial stiffness could provide a simple routine test that could help us to segregate the high risk candidates. Autonomic function assessment with HRV and HRR are simple discernible tools to detect the early autonomic changes, making them potential prognostic and diagnostic markers. Targeting at the precursor stage; preHTN, preDM and especially the co-existing individuals, where drug therapy is not recommended, would be of great boon to the society to retard or inhibit the development of DM and HTN; which are considered as the important causes for global mortality and morbidity. newline newline newline newline