Anxiety, mental stress and sudden cardiac arrest: epidemiology, possible mechanisms and future research.

dden cardiac arrest (SCA) is a leading cause of mortality a nd morbidity in affluent societies, which underscores the need to identify persons a t risk. The etiology of SCA is however complex, with predisposing and precipitating fa ctors interacting. Although anxiety and mental stress have been linked to SCA for decades , their precise role and impact remain unclear and the biological underpinnings are insufficiently understood. In this paper, we systematically reviewed various types of o bservational studies (total n = 20) examining the association between anxiety or mental str ess and SCA. Multiple methodological considerations challenged the summarizin g and interpretation of the findings. For anxiety, the overall picture suggests that it p redisposes for SCA in physically healthy populations (unadjusted OR = 2.44; 95% CI: 1.06–5.59; n = 3). However, in populations at risk for SCA ( n = 4), associations were heterogeneous but not significant. Anxiety may partly predispose to SCA by contributing to othe r risk factors such as cardiovascular disease and diabetes mellitus via mechanis ms such as unhealthy lifestyle and metabolic abnormalities. Mental stress appears to prec ipitate SCA, presumably by more directly impacting on the cardiac ion channels that con trol the heart’s electrical properties. This may lead to ventricular fibrillation, the a rrhythmia that underlies SCA. To advance this field of research, experimental studies that un ravel the underlying biological mechanisms are deemed important, and most easily designed f or mental stress as a precipitating factor because of the short timeframe. These proof-of-concept studies should examine the whole pathway from the brain to the autono mic nervous system, and eventually to cardiac ion channels. Ultimately, such studi es may facilitate the identification of persons at risk and the development of novel preventive st rategie