Antioxidants Supplementation During Exercise: Friends or Enemies for Cardiovascular Homeostasis?

Background The burden of cardiovascular diseases (CVDs) remains unclear in many regions of the world. Objectives The GBD (Global Burden of Disease) 2015 study integrated data on disease incidence, prevalence, and mortality to produce consistent, up-to-date estimates for cardiovascular burden. Methods CVD mortality was estimated from vital registration and verbal autopsy data. CVD prevalence was estimated using modeling software and data from health surveys, prospective cohorts, health system administrative data, and registries. Years lived with disability (YLD) were estimated by multiplying prevalence by disability weights. Years of life lost (YLL) were estimated by multiplying age-specific CVD deaths by a reference life expectancy. A sociodemographic index (SDI) was created for each location based on income per capita, educational attainment, and fertility. Results In 2015, there were an estimated 422.7 million cases of CVD (95% uncertainty interval: 415.53 to 427.87 million cases) and 17.92 million CVD deaths (95% uncertainty interval: 17.59 to 18.28 million CVD deaths). Declines in the age-standardized CVD death rate occurred between 1990 and 2015 in all high-income and some middle-income countries. Ischemic heart disease was the leading cause of CVD health lost globally, as well as in each world region, followed by stroke. As SDI increased beyond 0.25, the highest CVD mortality shifted from women to men. CVD mortality decreased sharply for both sexes in countries with an SDI >0.75. Conclusions CVDs remain a major cause of health loss for all regions of the world. Sociodemographic change over the past 25 years has been associated with dramatic declines in CVD in regions with very high SDI, but only a gradual decrease or no change in most regions. Future updates of the GBD study can be used to guide policymakers who are focused on reducing the overall burden of noncommunicable disease and achieving specific global health targets for CVD.

Current global health policy goals include a 25% reduction in premature mortality from noncommunicable diseases by 2025. In this 2-part review, we provide an overview of the current epidemiological data on cardiovascular diseases (CVD), its risk factors, and describe strategies aimed at reducing its burden. In part 1, we examine the global epidemiology of cardiac conditions that have the greatest impact on CVD mortality; the predominant risk factors; and the impact of upstream, societal health determinants (eg, environmental factors, health policy, and health systems) on CVD. Although age-standardized mortality from CVD has decreased in many regions of the world, the absolute number of deaths continues to increase, with the majority now occurring in middle- and low-income countries. It is evident that multiple factors are causally related to CVD, including traditional individual level risk factors (mainly tobacco use, lipids, and elevated blood pressure) and societal level health determinants (eg, health systems, health policies, and barriers to CVD prevention and care). Both individual and societal risk factors vary considerably between different regions of the world and economic settings. However, reliable data to estimate CVD burden are lacking in many regions of the world, which hampers the establishment of nationwide prevention and management strategies. A 25% reduction in premature CVD mortality globally is feasible but will require better implementation of evidence-based policies (particularly tobacco control) and integrated health systems strategies that improve CVD prevention and management. In addition, there is a need for better health information to monitor progress and guide health policy decisions.

Exercise induces physiological cardiac growth and protects the heart against pathological remodeling. Recent work suggests exercise also enhances the heart's capacity for repair, which could be important for regenerative therapies. While microRNAs are important in certain cardiac pathologies, less is known about their functional roles in exercise-induced cardiac phenotypes. We profiled cardiac microRNA expression in two distinct models of exercise and found microRNA-222 (miR-222) was upregulated in both. Downstream miR-222 targets modulating cardiomyocyte phenotypes were identified, including HIPK1 and HMBOX1. Inhibition of miR-222 in vivo completely blocked cardiac and cardiomyocyte growth in response to exercise while reducing markers of cardiomyocyte proliferation. Importantly, mice with inducible cardiomyocyte miR-222 expression were resistant to adverse cardiac remodeling and dysfunction after ischemic injury. These studies implicate miR-222 as necessary for exercise-induced cardiomyocyte growth and proliferation in the adult mammalian heart and show that it is sufficient to protect the heart against adverse remodeling.