Frame count reserve.

BACKGROUND The Doppler wire-derived (relative) coronary flow velocity reserve (CVR) that is used to evaluate functional significance of a coronary stenosis is a method performed only by interventional cardiologists. An angiographic method would be useful in the diagnostic catheterization laboratory. For this purpose, we investigated the relation between TIMI frame count reserve (FCR) and CVR. METHODS AND RESULTS In 38 patients, (relative) FCR of left anterior descending (LAD) and left circumflex coronary artery (LCx) was calculated by using manual, synchronized contrast agent injections and compared with (relative) CVR. In addition, vessel length was measured with an intracoronary guidewire and frame count flow velocity was calculated and compared with average peak velocity. There was a strong correlation between FCR and CVR (r=0.62, P<0.001) and between relative FCR and relative CVR (r=0.84, P<0.001). The LAD was significantly longer than the LCx (mean, 14.3+/-1.6 cm versus 11.4+/-1.8 cm, P<0.001), and, therefore, TIMI frame count of LAD was significantly higher than of LCx (mean basal 32.5+/-15.1 versus 23.6+/-9.1 and hyperemic 12.1+/-6.6 versus 8.7+/-3.2, both P<0.02). However, all flow velocity measurements and estimations of volume flow were not different for LAD compared with LCx. There were also no differences between mean FCR and CVR of LAD or LCx, of both vessels compared with each other and between mean relative FCR and relative CVR. CONCLUSIONS The (relative) frame count reserve can be used to estimate (relative) coronary flow velocity reserve.