Coronary Microvascular Dysfunction

Coronary Microvascular Dysfunction

Causing Cardiac Ischemia in Women

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Two-thirds of women who present with persistent symptoms and clinical signs of ischemia have no evidence of obstructive coronary artery disease (INOCA) on angiography.

Cardiac ischemia can be manifested by chest discomfort, shortness of breath, decreased exercise tolerance, and ST-segment or imaging abnormalities at rest or with stress.

Although women with a clinical presentation suggesting ischemic heart disease are often reassured after having a “normal” angiogram that their symptoms are not likely cardiac in etiology, in 13 of these women die from a cardiac cause within 10 years of the angiographic evaluation,and the most frequent adverse cardiac event is hospitalization for heart failure with preserved ejection fraction with an observed 10-fold higher rate compared with asymptomatic women (3.3% vs 0.3%).

For these women with INOCA, clinicians should consider the important, yet often overlooked, diagnosis of coronary microvascular dysfunction (CMD)—a small vessel disorder that confers an adverse prognosis in women for which there are available and continuously evolving diagnostic and treatment strategies.

Pharmacologic Strategies

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Management of cardiovascular risk factors includes control of dyslipidemia, diabetes, and hypertension, in addition to therapy with low-dose aspirin.

ACE inhibitors have been shown to improve CFR, exercise tolerance, and angina symptoms.

Carvedilol improves endothelial function.

Patients with abnormal vasodilator reserve have improved symptoms, less nitrate usage, and improved exercise tolerance after being treated with verapamil or nifedipine.

Statins not only lower cholesterol, but they also improve CFR.

The use of nitrates may or may not improve patients’ symptoms due to lack of smooth muscle in the microvasculature, and nitrate tolerance can be problematic with long-acting nitrates.

Ranolazine improves symptoms in patients with low CFR.

Conclusions

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The diagnosis of CMD should be considered in women with INOCA.

The risk for adverse cardiac events is relatively high in patients with CMD, despite the absence of obstructive CAD.

Therapeutic strategies can include optimal medical therapy of intensive statin, ACE inhibitors/ARB, low-dose aspirin, and therapeutic lifestyle change as outlined in ischemic heart disease guidelines.

Prospective registries are investigating INOCA in women and men, and randomized clinical outcome trials are examining treatment strategies.

Janet Wei, MD1; Susan Cheng, MD, MPH, MMSc1; C. Noel Bairey Merz, MD1