Influence of the extent of vascular territory on fractional flow reserve measurements.

摘要

Although measurements of the fractional flow reserve (FFR) provide accurate information on functional stenosis severity in many conditions, it remains unknown whether the extent of the vascular territory distal to the target lesion influences FFR calculations. Across a total of 16 selected coronary lesions intracoronary pressure during maximal hyperaemia was measured using intracoronary pressure wire both in the target artery distal to the lesion (great territory, site A) and in a branch originating distal to this lesion (small territory, site B). Coronary segments between both measurement sites were free from significant atherosclerosis, allowing comparison of FFR for different sizes of vascular regions but with identical epicardial resistance. The extent of vascular territory was assessed by means of the vascular score used in the Bari trial. The vascular territory was twice as great for site A as for site B: a mean vascular score of 8.7 versus 3.6.The mean diameter of the stenosis at the target lesion was 49 +/- 17%. For an identical epicardial resistance, the FFR was 77.3% +/- 14.6% for great vascular territories and 76.8% +/- 14.9% for small territories (p = 0.92, beta = 0.05).The mean difference between the FFR calculations was 0.5% +/- 3.4%. Thus, FFR measurements are not affected by the extent of the vascular territory underscoring the validity of the FFR concept. As a practical consequence, FFR measurements can be reliably carried out in cases of voluntary or obliged (eg. main stem lesions) access of the pressure wire into side branches.