Читать книгу Practical Cardiovascular Medicine - Elias B. Hanna - Страница 227

Women with typical angina frequently (~50%) do not have any significant CAD. In the WISE study, ~60% of women with chest pain undergoing coronary angiography (median age, 58) did not have any significant CAD, despite an abnormal stress test in the majority of them;¹³³ ~50% of women with chest pain and no obstructive CAD had microvascular dysfunction (as assessed by coronary flow reserve). ¹³⁴ Other studies showed a 70% combined prevalence of vasomotor abnormalities in women with possible or typical angina and no CAD.^6,120–122 As such, 50% of women without CAD continue to have chest pain for over a year, with a significant risk of MI (5.5%), HF (7.5%), stroke, and combined cardiovascular events (20%) at 6-year follow-up, higher than patients without persistent chest pain, albeit far lower than patients with CAD.^133-135 Microvascular dysfunction may be present without any stress test abnormality.¹³⁴ Perfusion stress PET or MRI is preferred.

The high rate of events on follow-up may be directly related to the following:

 Ischemic events/MI triggered by coronary vasospasm.

 Endothelial dysfunction and abnormal response to acetylcholine predicts the future development of obstructive CAD,¹³⁵ and a 14% risk of cardiac events, including progressive CAD, at 3 years.¹³⁶

 Since patients with spasm and endothelial dysfunction have underlying atherosclerosis, erosion of non-obstructive plaque is another potential mechanism of MI. A dysfunctional endothelium may contribute to plaque destabilization and erosion because of its reduced antioxidative potential.

The chicken or the egg dilemma: Diastolic dysfunction with elevated LVEDP may be the cause but also the consequence of microvascular dysfunction, especially in patients without significant LV concentric remodeling. This partly explains HF events in these patients.¹³⁷

In sum, abnormalities of coronary flow may be due to obstructive CAD, coronary epicardial spasm, or microvascular spasm/ dysfunction. While obstructive CAD is associated with the highest risk of events, abnormal vasomotion is associated with an intermediate risk of events, including MI, arrhythmias, and progressive CAD, higher than in patients with no CAD and normal vasomotion.