Shift work and subclinical atherosclerosis: recommendations for fatty liver disease detection.

SOOKOIAN S; PIROLA CJ,

ATHEROSCLEROSIS

ELSEVIER IRELAND LTD

Año: 2009 vol. 207 p. 346 - 347

0021-9150

We have read with great interest the article by Puttonen S, et al. about the association between shift work and subclinical atherosclerosis in young people [1]. The authors reported that shift workers showed a higher carotid intima-media thickness (IMT) and a 2.2-fold increased risk of carotid plaques than those observed in day workers. Unfortunately, shift work schedule has been associated with several deleterious effects on the cardiovascular and metabolic systems. For instance, shift work was associated with a significant high risk of death due to ischemic heart disease [2; 3]. In fact, results from large prospective studies showed that shift work is associated with myocardial infarction [4]. A recently published study showed that shift work is a risk factor for myocardial infarction even at younger ages [5]. Otherwise, we observed that shift workers show most of the risk factors of the cardiometabolic syndrome, including elevated body mass index, waist-hip ratio, diastolic blood pressure, fasting insulin, HOMA index and triglycerides [6]. In addition, our results emphasize the presence of low-grade inflammation in shift workers, which may be a contributing factor to the health problems that characterize the shift work. Taken together, all these data are of remarkable importance as shift work contributes to the morbimortality of cardiovascular diseases in young exposed people as emphasized by Puttonen et al. [1]. In addition, it is worth mentioning that shift workers represent approximately 20 % of the work force worldwide, including the developed world. Based on the above-mentioned comments, we believe that a final observation should be added. In the in the last couple of years, several epidemiological studies showed that nonalcoholic fatty liver disease (NAFLD), a highly prevalent disease characterized by excess fat accumulation in the liver, is associated with an increased risk for cardiovascular disease [7]. Moreover, NAFLD is now considered the hepatic manifestation of the cardiometabolic syndrome [8]. In a recent systematic review of the literature that included 3497 individuals, we observed that patients with hepatic steatosis have an increase of 13 % of carotid IMT in comparison with individuals without fatty liver [9]. Hence, in the light of all these observations above-described about the high risk for cardiovascular disease that individuals exposed to a working schedule of shift work have, and considering that shift workers show most of the features of the cardiometabolic syndrome, it is reasonable to postulate that shift workers have also a high prevalence of NAFLD. Therefore, we can conclude that it seems mandatory to assess the overall cardiovascular risk of rotating shift workers, including the systematic detection of fatty liver disease by a non invasive, cheap and readily available imaging method, such liver ultrasound. In addition, the screening strategy may also include a systematic measurement of circulating concentrations of the liver transaminases, alanine aminotransferase (ALT) and aspartate aminotransferase (AST). These two liver enzymes besides being a surrogate marker of NAFLD were previously shown to have a high predictive value for coronary events, independent of the traditional risk factors and features of the metabolic syndrome [10]. Moreover, by adding to these biochemical test other simple measurements, such as BMI, waist circumference and HOMA index, a very cheap and highly predictive score for differentiating simple steatosis from non-alcoholic steatohepatitis may be calculated [11]. This proposal may provide benefits on primary prevention and in the decision to treat the existing but not diagnosed cardiovascular and liver disease in young individuals. Accordingly, NAFLD may contribute to the systemic inflammation and insulin resistance, landmarks of the cardiometabolic syndrome. In this setting, type I angiotensin II receptor blockers are promising therapeutics agents [12].