Emotional triggering of cardiac events

Abstract

Psychological factors may contribute not only to the evolution of coronary atherosclerosis and long-term risk of coronary heart disease, but also to the triggering of acute cardiac events in patients with advanced atherosclerosis. Evidence for emotional triggering of cardiac events derives both from population-based studies of hospital admissions and sudden deaths following major traumas such as earthquakes and terrorist incidents, and from individually based interview studies with survivors of acute coronary syndromes (ACS). The latter indicate that acute anger, stress and depression or sadness may trigger ACS within a few hours in vulnerable individuals. The psychobiological processes underlying emotional triggering may include stress-induced haemodynamic responses, autonomic dysfunction and parasympathetic withdrawal, neuroendocrine activation, inflammatory responses involving cytokines and chemokines, and prothrombotic responses, notably platelet activation. These factors in turn promote coronary plaque disruption, myocardial ischaemia, cardiac dysrhythmia and thrombus formation. The implications of these findings for patient care and ACS prevention are outlined.

Introduction

Cardiovascular disease is one of the main causes of serious illness, and a major cause of death and reduced quality of life. The costs of cardiovascular disease, including healthcare costs, the price of unpaid care and loss of earnings, were estimated at €169 billion in 2003 (Leal et al., 2006). Coronary heart disease (CHD) is the largest single cause of death in Europe, accounting for 21% of male and 22% of female deaths (Allender et al., 2008). It is also the leading cause of death in people aged less than 75 years (20% male and 19% female deaths). However, death rates have been declining for the past three decades in many countries, due primarily to improvements in risk factor profile, and also to increased survival following acute coronary events. This means that the prevalence of diagnosed CHD in the population has been rising. Recent figures from the USA indicate that 6.5% of the population have a history of heart attack (myocardial infarction) or angina pectoris (Anon., 2007).

There is an extensive literature relating psychosocial factors with the development of CHD (Everson-Rose and Lewis, 2005, Kuper et al., 2005). The condition underlying CHD is coronary atherosclerosis, a progressive process of arterial wall thickening due to lipid deposition, inflammation and smooth muscle infiltration (Hansson, 2005). The psychosocial factors implicated in both atherosclerosis and CHD include low socioeconomic status (SES), chronic stress exposure, particularly in the work place, and aspects of the social environment such as social isolation and low social support. In addition, emotional factors including depression, anxiety, anger and hostility are thought to contribute to the development of CHD (Suls and Bunde, 2005, Steptoe, 2006). This research has been primarily concerned with long-term aetiology, and with demonstrating that exposure to psychosocial risk factors promotes accelerated atherosclerosis and higher rates of CHD incidence. There is, however, another way in which emotional factors might contribute to cardiovascular disease, and this is through the stimulation of acute cardiac events such as myocardial infarction (MI), unstable angina, or sudden cardiac death. Such cardiac events typically occur in people with advance coronary atherosclerosis. The emotional factors involved in these situations are not necessarily the same as those implicated in long-term aetiology, since they act over a much shorter time scale. The purpose of this review is to summarize the evidence for emotional triggering of cardiac events, and to outline the psychophysiological processes that stimulate the pathological responses underlying acute coronary syndromes (ACS, comprising myocardial infarction and unstable angina) or sudden cardiac death.