Grant: Project Grant

Although more women than men die annually of coronary artery disease (CAD), nearly one half of women presenting with chest pain are found to have non-obstructive CAD (NoCAD). Historically, these patients were often reassured without consideration for diagnostic or treatment options. More recently, evidence has shown that nearly 50% of women with chest pain and NoCAD have occult disease in the small vessels of the heart, referred to as coronary microvascular dysfunction (CMD), which has been shown to carry a heightened risk for future cardiovascular events. Current characterization of patients with chest pain syndromes and NoCAD rely on invasive testing that lack standardized protocols and use pharmacological agents including adenosine, which are often poorly tolerated in patients. This has limited the use of these diagnostic tests in the evaluation of patients with NoCAD, leaving many patients with CMD undiagnosed and untreated. Recently, oxygen sensitive magnetic resonance imaging (OS-CMR) using a combination of breathing manoeuvres has been shown to be capable of identifying microvascular changes in the heart in patients with obstructive sleep apnea. Given the less invasive nature of this technique, we intend to study this novel diagnostic tool to assess its ability to detect CMD in women. We will also evaluate whether breathing manoeuvres during OS-CMR can detect CMD as accurately as with the administration of adenosine. We expect that our study will show that women with CMD will have inadequate oxygenation response to breathing manoeuvres that will be identified on OS-CMR. Additionally OS-CMR with breathing manoeuvres will be able to detect CMD as accurately as adenosine. Our results will support the use of OS-CMR as a non-invasive diagnostic tool in the assessment of women with chest pain and NoCAD, which will allow physicians to better identify patients with CMD and provide the foundation for which future treatment can be studied.