Female patients presenting with persistent chest pain despite no obstructive coronary artery disease have impaired prognosis. Stress tests are often positive or inconclusive. As much as 20% of women with chest pain and minimal angiographic CAD have evidence of myocardial ischemia, suggesting impaired coronary microcirculation. The index of microvascular resistance (IMR) is a method for indirectly investigating microvascular function in the cardiac catheterization laboratory.

66 female patients, age 30-70 years, with chest pain and "normal" or near normal coronary angiograms will be included. After coronary physiologic evaluation, patients will be randomized in a double blind study to rosuvastatin 20 mg/day or matching placebo tablets for altogether 6 months.

The investigators hypothesize that:

1. A substantial number of women with chest pain and normal or minimal pathology on angiograms have microvascular dysfunction defined by a raised IMR.
2. Statins, based on its pleiotropic action will improve endothelial function and thereby IMR.

Inclusion Criteria:

1. Female gender
2. Age 30 - 70 years
3. Chest pain suggestive of symptomatic coronary artery disease
4. A coronary angiogram with no or minimal coronary artery disease
5. Fractional flow reserve value over 0,80

Exclusion Criteria:

1. Male gender
2. Age under 30 years or over 70
3. Coronary artery stenosis ≥ 33 % in any epicardial vessel
4. Fractional flow reserve value ≤ 0,80
5. Pregnant or nursing women
6. Women of childbearing potential not using contraception
7. Short life expectancy
8. Uncontrolled endocrinological disease
9. Arterial hypertension
10. Structural heart disease
11. Significant mental disorder, including dementia
12. Inability to comply with the protocol -

Analyses of the study will start within a few weeks or months. Publication planned in 2017