Grade 3-Complete perfusion antegrade flow into the bed distal to the obstruction occurs as promptly as antegrade flow into the bed proximal to the obstruction, and clearance of contrast material from the involved bed is as rapid as clearance from an uninvolved bed in the same vessel or the opposite artery. However, the rate of entry of contrast material into the vessel distal to the obstruction or its rate of clearance from the distal bed (or both) is perceptibly slower than its flow into or clearance from comparable areas not perfused by the previously occluded vessel (eg, opposite coronary artery or the coronary bed proximal to the obstruction). Grade 2-Partial perfusion contrast material passes across the obstruction and opacifies the coronary artery distal to the obstruction. Grade 1-Penetration without perfusion contrast material passes beyond the area of obstruction but fails to opacify the entire coronary bed distal to the obstruction for the duration of the cineangiographic filming sequence. TIMI flow grade was assessed at the angiographic core laboratory as previously defined 1 : Grade 0-No perfusion no antegrade flow beyond the point of occlusion. Qualitative Angiographic Analysis: TIMI Flow Grade Assessment The results of this study were published previously. To standardize the assessment of coronary flow and develop a simple continuous index of coronary flow, the number of cineframes required for contrast material to first reach standard distal coronary landmarks (the TIMI frame count) was determined after thrombolysis in the TIMI 4 trial. Furthermore, in addition to its subjective nature, the conventional flow-grading system is categorical, and no continuous angiographic index of coronary flow currently exists. Variability in the visual assessment of this end point hampers comparisons of flow data between agents and between trials. 1 Although this widely used method of grading coronary flow has been a valuable tool for comparing the efficacy of thrombolytic agents and identifying patients at higher risk for adverse outcomes, 2 3 4 5 6 7 the assessment of this angiographic end point is subjective. The TIMI flow-grading system classifies successful reperfusion after thrombolysis as either grade 2 (partial) or grade 3 (complete) flow. Disordered resistance vessel function may account in part for reductions in flow in the early hours after thrombolysis. The mean 90-minute CTFC among nonculprit arteries (25.5☙.8) was significantly higher (flow was slower) compared with arteries with normal flow in the absence of acute MI (21.0☓.1, P<.001) but improved to that of normal arteries by 1 day after thrombolysis (21.7☗.1, P=NS).Ĭonclusions The CTFC is a simple, reproducible, objective, and quantitative index of coronary flow that allows standardization of TIMI flow grades and facilitates comparisons of angiographic end points between trials. No correlation existed between improvements in CTFCs and changes in minimum lumen diameter ( r=−.05, P=.59). The mean CTFC in culprit arteries 90 minutes after thrombolytic administration followed a continuous unimodal distribution (there were not subpopulations of slow and fast flow) with a mean value of 39.2☒0.0 frames, which improved to 31.7☑2.9 frames by 18 to 36 hours ( P<.001). Therefore, the longer LAD frame counts were corrected by dividing by 1.7 to derive the corrected TIMI frame count (CTFC). In 78 consecutive normal arteries, the left anterior descending coronary artery (LAD) TIMI frame count (36.2☒.6 frames) was 1.7 times longer than the mean of the right coronary artery (20.4☓.0) and circumflex counts (22.2±4.1, P<.001 for either versus LAD). The TIMI frame-counting method was reproducible (mean absolute difference between two injections, 4.7☓.9 frames, n=85). Methods and Results In normal patients and patients with acute myocardial infarction (MI) (TIMI 4), the number of cineframes needed for dye to reach standardized distal landmarks was counted to objectively assess an index of coronary blood flow as a continuous variable. Customer Service and Ordering Informationīackground Although the Thrombolysis in Myocardial Infarction (TIMI) flow grade is a valuable and widely used qualitative measure in angiographic trials, it is limited by its subjective and categorical nature.Stroke: Vascular and Interventional Neurology.Journal of the American Heart Association (JAHA).Circ: Cardiovascular Quality & Outcomes.Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).
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