Fractional flow reserve: a review

Coronary angiography remains far and away the most accurate morphologic assessment of the lumen of the epicardial coronary arteries. Although non-invasive imaging is rapidly advancing, the temporal and spatial resolution of coronary angiography is still unsurpassed and it will therefore remain as a roadmap for interventional cardiologists and cardiac surgeons. Most non-invasive cardiologists still consider a coronary angiogram as “invasive” (although this is a debatable classification in 2008), but welcome the high level of anatomical information. However, in contrast to its topographical precision, angiography is limited in gauging the functional repercussions of coronary stenoses. Yet, functional severity of atherosclerotic narrowings is the single most important prognostic factor in patients with documented coronary artery disease. This was recently highlighted in several large meta-analyses: the estimated annualised rate of myocardial infarction or cardiac death was approximately 0.5% per year after a normal myocardial perfusion imaging or a normal stress echocardiogram in patients with unknown coronary anatomy.1 w1 In addition, the DEFER trial showed that the annual rate of death or myocardial infarction is approximately 1% in patients with angiographically documented epicardial coronary stenoses that are not functionally significant.2 In daily practice, however, non-invasive testing is performed in a minority of patients undergoing angioplasty.w2 Since the angiographic degree of stenosis is a poor tool to establish the functional significance of a given stenosis, a large number of inappropriate decisions are taken regarding revascularisation.3 Thus, the combination of highly accurate anatomic assessment and precise functional information is indispensable to tailor the treatment of patients with suspected or known coronary artery disease. Accordingly, the combination of coronary angiography and pressure derived fractional flow reserve in the catheterisation laboratory emerges as the only true “all-in-one” approach as it combines anatomy, physiology, and the possibility of “ad hoc” treatment. The present review will …