Conclusions
Transthoracic Doppler echocardiography is a reliable way to study CFVR with the advantage of being non-invasive, available and inexpensive. It is used to measure flow reserve in both stenosed and normal epicardial coronary arteries (every one of the three major coronary arteries can be evaluated although most of the experience is with CFVR measurement in LAD). In the presence of coronary artery stenosis CFVR is useful to detect a significant stenosis, to assess the functional significance of intermediate stenosis and to monitor for restenosis during follow-up after coronary revascularisation. In patients with anatomically normal epicardial coronary arteries impaired CFVR is a marker of microvascular dysfunction in different clinical settings.