Acute cardiac coronary events and stress generated at a population level

Abstract

Title: Acute cardiac coronary events and stress generated at a population level. Introduction and Literature Review: There is increasing recognition that mental stress can trigger acute clinical events in susceptible patients with pre-existing coronary artery disease (CAD). It is thought that stress brings about haemodynamic and neuroendocrine responses characterised by the release of catecholamines and corticosteroids, resulting in an increase in heart rate, cardiac output, and blood pressure, as well as changes in processes involved in haemostasis and thrombosis. In addition, these stress-induced responses may also directly promote atherosclerosis and dysfunction of the coronary endothelium, or trigger lethal arrhythmias. In patients with pre-existing CAD, these physiological changes may increase vulnerability to clinical events such as myocardial ischaemia, coronary thrombosis, myocardial infarction, and ventricular arrhythmias. This emotional triggering of acute cardiac events has been extensively investigated, with the majority of studies using a retrospective approach. One method to investigate the influence of psychological stress on the incidence of acute cardiac coronary events is to conduct an ecological study which utilises routine data to analyse temporal trends in order to look for the effects of a real world event in a study population that is stressed by the event. Malta is an island with a population of about 400,000 and one acute public general hospital that lends itself perfectly for a population study. Two events identified as potential sources of emotional stress on the Maltese population are political contests and important international football tournaments. The psychological stresses provoked by the 2008 Maltese general election and the 2008 European Cup of Nations football tournament, and their effects on acute cardiac coronary events on the Maltese public, were adopted to represent potential stressors acting on a typical study population as a means to investigate the impact of public stress on CAD.

Aim: To test the following {(null hypothesis": that there is no relationship between the excitement generated by a hotly debated national political event or the passion evoked by an international football tournament, and the incidence of acute cardiac coronary events at a population level. Methods: A general election in Malta was held on 8 March 2008. Data on all Maltese patients who were admitted to Saint Luke's Hospital (SLH)/Mater Dei Hospital (MOH) with ST segment elevation myocardial infarction (STEM!) and non-ST segment elevation acute coronary syndromes (NSTE-ACS), as well as on Maltese residents who died from myocardial infarction (MI) and ischaemic heart disease (lHDL were collected during the 6 weeks from 9 February to 22 March 2008 (period 2). Similar data was collected in the 6 weeks during which the EURO 2008 football tournament was being played (1 June-13 July 2008 (period 3))1 and during two other control 6-week periods (1 October-12 November 2007 (period 1) and 9 February-22 March 2009 (period 4)). A Poisson regression analysis was used to statistically compare study periods 2 and 3 to each of the 2 control periods.

Results: The Maltese population in 2008 stood at around 413,000 of which 315,357 were eligible to vote. There were 117, 184, 127, and 130 admissions with STEMI and NSTE-ACS during periods 1, 2, 3, and 4 respectively, suggesting a statistically significant increase in the number of registered ACS cases during the election period when compared to each of the control periods (p<0.001 vs period 1; p=0.003 vs period 4). There were no significant differences in the rates of ACS admissions during the EURO study period compared to the 2 control periods. Baseline characteristics in terms of age, gender, history of CAD and category of ACS were well matched. Risk factor analysis yielded borderline significant differences in terms of diabetes mellitus and family history of CAD. There were 641 1071 74, and 103 deaths among Maltese residents from MI and IHD during periods 11 21 31 and 4 respectively, suggesting a significant rise in the number of recorded deaths during the election study period in comparison to the first control period (p=O.003). Conversely, there were significantly more deaths due to MI and IHD during the second control period compared to the EURO study period (p=O.029). During week 5, corresponding to the week immediately following election day, 25 deaths were recorded in period 2, compared to 11, 13, and 11 for the same week during periods 1, 3, and 4 respectively, indicating a significant increase in CAD mortality rate during the election period relative to each of the control periods (p=O.025 vs period 1; p=0.024 vs period 4).

Conclusions: The results challenge the {{null hypothesis" by suggesting that the incidence of both non-fatal, as well as fatal, acute cardiac coronary events was increased during the election period when compared to control periods. This may primarily be explained by the effects of heightened acute mental stress levels that are generated among the Maltese population by public events such as a general election.