In this issue of Cardiovascular Endocrinology the ongoing controversy concerning the association of low vitamin D levels with the metabolic syndrome is examined by Shanin et al. at the Mansoura School of Medicine, Egypt. Vitamin D has come to be recognized as a multi-faceted hormone that may modify the risk of common cardiovascular and metabolic diseases. The investigators compared a group of obese women satisfying a widely accepted definition of the metabolic syndrome with non-obese first-degree relatives and unrelated healthy women. The women with the metabolic syndrome had significantly lower 25-hydroxy vitamin D levels compared with the non-obese control groups. Among the first-degree relatives who would be expected to share genetic and environmental dispositions to metabolic syndrome low vitamin D status was associated with an unfavourable cardiometabolic profile. While a cross-sectional study does not provide a sound basis for determining cause-and-effect relationships some general findings in this report are of interest from a public health perspective. In particular, according to their definition the authors found a high prevalence of vitamin D deficiency among the women in their study, an observation that is in line with other studies from the Middle East and Gulf states. While obesity may reduce the bioavailability of vitamin D the authors hypothesize that the impact of skin pigmentation and veiling should also be considered. Given the high prevalence rates of obesity, the metabolic syndrome and type 2 diabetes in this region of the world the pathophysiological implications of vitamin D deficiency merit further evaluation in prospective, and perhaps interventional, studies in these populations. The authors point out that Egypt offers a unique mix of different races and ethnicities that might be of value in this regard.
Cardiac failure is associated with multiple endocrine and biochemical disturbances, among which whole body insulin resistance has been reported. Whether impaired insulin action is a modifiable prognostic factor in heart failure patients remains to be determined. Exercise has a well-established role in the management of chronic heart failure, and may also improve insulin action. White and colleagues at the Montreal Heart Unit report the results of an interventional non-pharmacological study that combined aerobic and resistance exercise training on exercise capacity and glucose regulation in diabetic patients with stable symptomatic heart failure. The authors report that aerobic capacity and insulin resistance (assessed using homeostasis model assessment) improved in the patients with the most severe degrees of functional and metabolic impairment. The supervised intervention was safe and most of the patients were able to comply with the exercise regimen. Additional studies are warranted to confirm these observations.
All the components of the renin-angiotensin system (RAS) are present in the brain. Orally administered angiotensin converting enzyme inhibitors and angiotensin II receptors blockers can cross the blood-brain barrier and influence pressor responses. To test the hypothesis that central RAS activity might have implications for age-related cardiac dysfunction Groban and her colleagues from Wake Forest School of Medicine used a transgenic rat model of disrupted glial angiotensinogen. The investigators conclude that disruption of brain RAS directly or indirectly provides protection against mid-life increases in body weight gain, blood pressure, left ventricular stiffness and reductions in exercise tolerance. However, when considering possible clinical implications of their findings they note that their transgenic rat model does not share the deleterious rise systolic blood pressure that usually accompanies the ageing process.
Finally, Aziz et al. provide a reminder that while primary heart tumours or metastases to the heart are uncommon in clinical practice, autopsy studies suggest they might not be such a rare manifestation of metastatic cancer. In their case report the authors present data supporting a diagnosis of a thyroid angiosarcoma (itself a rare cancer) mimicking massive pulmonary embolism.
Conflicts of interest
There are no conflicts of interest.