Sex Difference of Coronary Microvascular Dysfunction in Patients With Non-obstructive Coronary Artery Disease

Transthoracic echocardiographic assessments will be performed using an ultrasound device (Vivid E95, General Electric Healthcare, Liestal, Switzerland). Color Doppler flow of the distal left anterior descending artery was examined from the modified apical four-chamber view of the anterior interventricular groove. Pulsed-wave Doppler registered blood flow velocity patterns using a sample volume (2-3.0 mm) placed on the color signal. The ultrasound beam was aligned parallel to the vessel flow. The velocity scale of color Doppler was set to 0.21 m/s. Coronary flow Doppler images were acquired at baseline and at 1, 2, and 3 min after adenosine infusion in the same part of the artery. Anti-anginal medications, including calcium channel blockers, were discontinued before the study.