Metformin therapy improves coronary microvascular function in patients with polycystic ovary syndrome and insulin resistance

BACKGROUND: Women with polycystic ovary syndrome (PCOS) are thought to have increased cardiovascular risk. Metformin therapy reduces whole-body insulin resistance (IR) in patients with type-2 diabetes mellitus (DM). OBJECTIVE: As insulin resistance accompanying PCOS may be reversed by metformin therapy, we hypothesized that metformin therapy might improve coronary microvascular functions in women with PCOS and IR. PATIENTS AND METHODS: We treated 16 women with PCOS and IR with metformin, and measured coronary flow reserve (CFR) at the beginning and after 6 months of metformin therapy using transthoracic second-harmonic Doppler echocardiography. RESULTS: At the end of the 6 months of metformin therapy, baseline coronary diastolic peak flow velocity (DPFV) did not change significantly (from 24.6 +/- 4.3 to 23.0 +/- 3.1, P = 0.106); however, hyperaemic coronary DPFV (from 68.2 +/- 12.7 to 74.5 +/- 9.7, P = 0.08), and CFR (from 2.75 +/- 0.48 to 3.3 +/- 0.5, P = 0.016) was significantly improved by metformin therapy. CONCLUSION: In women with PCOS, coronary microvascular function and CFR are significantly improved by 6 months of therapy with metformin.