Dr Esben Strodl: Psychological factors associated with the frequency of angina and the role of mediating variables.
Coronary heart disease (CHD) is the most burdensome disease in Australia. The disease can manifest itself in the form of angina, myocardial infarction (MI), and sudden coronary death. There is a large body of research showing that psychological factors are associated with various manifestations of CHD. Psychological interventions will have a greater effect, and be more cost-efficient, if patients are identified who are most at risk of having their angina triggered by psychological variables.
Three possible moderators were identified from a literature review: gender, a history of MI, and a history of coronary artery bypass graft (CABG). Three studies were designed to test the hypothesis that these three variables would moderate the relationship between psychological factors and angina frequency.
Study One examined 204 patients hospitalised with unstable angina. The results showed a relationship between reactive anger and angina frequency in women, but not men, during the acute phase of the angina. The strongest moderator appeared to be having a recent history of a CABG. Because this finding of prior cardiac procedures (CABG or angioplasty) was so novel, it was important to explore corroborating evidence that having such a procedure moderated the relationship between psychological factors and coronary chest pain. This was achieved by analyzing data from the Older cohort of ALSWH for 543 women who reported having been diagnosed with CHD but reported no history of these procedures, and 481 women who had had these procedures. The analysis confirmed that having a heart intervention did moderate the relationship between psychological factors and chest pain in older women. Time pressure in 1996 predicted the presence of chest pain three years later in those with CHD but without a history of prior cardiac heart procedures. In contrast, a diagnosis of depression during the three-year period predicted chest pain in those who reported having undergone a cardiac procedure. The third study explored three possible psychophysiological mediators to explain the relationship between psychological factors and angina frequency. A sample of 30 stable angina patients was used for the study. Heart rate variability was strongly correlated with angina frequency with evidence of moderating effects of history of MI and CABG, but not gender.
On the basis of the findings from this thesis, combined with the findings of the literature, it is concluded that there is an association between psychological factors and angina frequency, but that these relationships are complex, being affected by moderators such as gender, history of MI and history of CABG. Future research is needed to elucidate the links between psychological factors and angina to help treat angina episodes that are induced by psychological factors