The overall goal of this project is to clarify the mechanisms and pathophysiology of how psychological stress contributes to Major Adverse Cardiovascular Events (MACE) in women despite having no obstructive CAD. Through this proposal, the research team expects to have an improved understanding of the relationships between mental stress and coronary microvascular dysfunction in women.
One-third to one-half of women with chest pain who are suspected of having myocardial ischemia and undergo coronary angiography are actually found to have no obstructive coronary artery disease (CAD) (\<50% luminal stenosis) and thus are often reassured and dismissed without a cardiac diagnosis or therapy. Current evidence suggests that a large proportion of these women have coronary microvascular dysfunction (CMD) and are at significantly increased risk of major adverse cardiovascular events (MACE), including myocardial infarction, heart failure, and sudden cardiac death. However, because of substantial knowledge gaps, these patients also have recurrent hospitalizations for chest pain, reduced health-related quality of life, and comparable disability and healthcare costs to obstructive CAD patients. Cardiac rest/stress positron emission tomography (PET) imaging can detect impaired myocardial flow reserve (MFR) and diagnose CMD. However, therapeutic strategies are poorly developed, with limited studies to inform clinicians on the treatment of CMD.
Comorbid psychological factors such as anxiety and depression are prevalent in women with persistent angina, and stress can contribute to and exacerbate angina, implicating the autonomic nervous system (ANS) as one mechanistic pathway in CMD-related ischemia and MACE. The preliminary data indicate that women with CMD have ANS dysfunction with sympathetic predominance compared to non-CMD controls. The research team has shown that women have more mental stress ischemia (MSI) and stress-induced peripheral microvascular vasoconstriction compared to men. MSI is an important prognostic marker with an estimated two-fold increase in MACE, including mortality, regardless of the severity of CAD.
The research team posits that an improved understanding of psychological stress reactivity in CMD patients will help tease out the underlying mechanisms contributing to adverse outcomes in CMD-related ischemia and provide new treatment targets to reduce symptom burden and MACE. The overall goal of this project is to clarify the mechanisms and pathophysiology of how psychological stress contributes to MACE in women despite having no obstructive CAD. The research team has also shown that coronary microvascular responses to mental stress are reflected in the peripheral microvascular circulation. This proposal addresses an important knowledge gap in an understudied population and is a direct extension of their prior work. Findings from this work have the potential to inform therapeutic strategies in CMD, a problem that impacts an estimated 3 million American women. The unifying hypothesis is that women with CMD have exaggerated sympathetic activation and abnormal vasoreactivity to mental stress, which predisposes them to adverse outcomes even in the absence of obstructive CAD.
Three groups of post-menopausal women will be compared: (1) symptomatic women with no obstructive CAD who have CMD ; (2) symptomatic women with chronic obstructive CAD (oCAD); and (3) asymptomatic control women with no prior history of CAD or angina, who are age-matched to the CMD women. The oCAD group will serve as a comparison group since these women represent the prevailing paradigm of ischemia from obstructive stenosis while sharing common cardiovascular risk factors that could confound the findings.
No study has comprehensively characterized mental stress reactivity by pairing autonomic responses and vascular reactivity in women with CMD, and with follow-up of angina and quality of life (QoL). This study would provide critical data on the clinical significance of these measures in the CMD population.
