Timi Frame Count

To overcome the above limitations associated with the TIMI flow grade classification scheme, we have recently described a more objective and precise method of estimating coronary blood flow, in which the number of cineframes required for dye to reach standardized distal landmarks are counted, called the TIMI frame count (2). In the first frame used for TIMI frame counting, a column of dye touches both borders of the coronary artery and moves forward (Fig. 1). In the last frame, dye begins to enter (but does not necessarily fill) a standard distal landmark in the artery (Fig. 1). These standard distal landmarks are as follows: in the right coronary artery the first branch of the posterolateral artery; in the circumflex system the most distal branch of the obtuse marginal branch, which includes the culprit lesion in the dye path; and in the left anterior descending (LAD) artery the distal bifurcation which is also known as the "moustache," "pitch fork," or "whales tail" (Fig. 1). These frame counts are corrected for the longer length of the LAD by dividing by 1.7 to arrive at the corrected TIMI frame count (CTFC) (2).

In contrast to the conventional TIMI flow grade classification scheme, the CTFC is quantitative rather than qualitative, it is objective rather than subjective, it is a continuous rather than a categorical variable, and it is reproducible (2). Indeed, with respect to

Left Circumflex Artery Timi Frame Count

Fig. 1. The TIMI frame counting method. In the first frame (lower left panel), a column of near or fully concentrated dye touches both borders of the coronary artery and moves forward. In the last frame (second column), dye begins to enter (but does not necessarily fill) a standard distal landmark in the artery. These standard distal landmarks are as follows: the first branch of the posterolateral artery in the right coronary artery (upper panel, third column); in the circumflex system the most distal branch of the obtuse marginal branch which includes the culprit lesion in the dye path (mid panel, third column); and in the left anterior descending artery the distal bifurcation which is also known as the "moustache", "pitch fork" or "whales tail" (lower panel, third column).

Fig. 1. The TIMI frame counting method. In the first frame (lower left panel), a column of near or fully concentrated dye touches both borders of the coronary artery and moves forward. In the last frame (second column), dye begins to enter (but does not necessarily fill) a standard distal landmark in the artery. These standard distal landmarks are as follows: the first branch of the posterolateral artery in the right coronary artery (upper panel, third column); in the circumflex system the most distal branch of the obtuse marginal branch which includes the culprit lesion in the dye path (mid panel, third column); and in the left anterior descending artery the distal bifurcation which is also known as the "moustache", "pitch fork" or "whales tail" (lower panel, third column).

variability, the mean absolute value of the difference between two consecutive hand injections of the infarct-related artery was only 4.7 ± 3.9 frames (n = 85) (2). Other groups, such as Ivanc and Ellis et al., have shown even better measures of reproducibility (11). These authors examined angiograms on two separate occasions separated in time by 6 mos, and found a correlation of 0.97 in their readings over time and a correlation of 0.99 among three different observers (11). There was a 0.7-2.0 frame difference between observers (11). In a recent study where two experienced angiographic core laboratories (Global Use of Strategies to Open Occluded Coronary Arteries [GUSTO] and TIMI) analyzed the same films for a fibrinolytic trial, there were discrepancies in 21% of TFG readings (41 out of 194, k = 0.76); however, excellent concordance in trial results were seen using the CTFC (overall median difference = 0 frames) with no significant difference being observed between the two core laboratories (12).

Normal flow in normal arteries in the absence of acute myocardial infarction (MI) has been found to be 21.0 ± 3.1 frames (n = 78)(2), with the 95% confidence interval for normal flow extending from >14 frames to <28 frames. Despite differences in the length of the coronary arteries, the force of injections, the diameter of the arteries, heart rates, cardiac output, and catheter engagement, we have found that the standard

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