Corrected TIMI Frame Count: Applicability in Modern Digital Catheter Laboratories When Different Frame Acquisition Rates Are Used Kunadian Vijayalakshmi, 1 MSc, MBBS, MRCP, Victoria J. Ashton, 2 MSc, Robert A. Wright, 1 MD, FRCP, James A. Hall, 1 MA, MD, FRCP, Michael J. Stewart, 1 MD, FRCP, Adrian Davies, 1 BSc, FRCP, and Mark A. de Belder, 1 * MA, MD, FRCP The original description of the TIMI frame count (TFC) method was based on angiograms acquired at 30 f/sec. Modern digital angiograms are acquired at lower frame rates (between 12.5 and 25 f/sec). Coronary angiography was acquired at 12.5 and 25 f/sec after 200 g of intracoronary glyceryl trinitrate. Results of the corrected TIMI frame count (cTFC) at 12.5 and 25 f/sec for each vessel were: right coronary artery, 19.5  5.2 and 20.4  6.6 (P  0.15); circumflex artery, 25.6  8.2 and 25.9  8.7 (P  0.5); and left anterior descending artery, 22.5  8.1 and 23.8  10.4 (P  0.15), respectively. The mean differ- ence in the TFC between two injections by the same operator and by two operators was 0.4 (P  0.7) and 0.4 (P  0.2), respectively. The mean difference in the TFC for repeat measurements by the same observer and between two observers was 0.26 (P  0.3) and 0.06 (P  0.8), respectively. We confirm that the cTFC is a quantitative method to assess coronary flow that can be applied in a modern digital laboratory. Catheter Cardiovasc Interv 2004;63:426 – 432. © 2004 Wiley-Liss, Inc. Key words: coronary angiography; intracoronary glyceryl trinitrate; coronary flow INTRODUCTION The corrected TIMI frame count (cTFC) method counts the number of cine angiographic frames required for the contrast to travel from the proximal end of the coronary arteries to standardized distal coronary landmarks (correct- ing for the larger length of the left anterior descending artery compared with the other arteries). This method has been validated and proposed as a simple, reproducible, objective, and quantitative index of coronary flow that allows stan- dardization of TIMI flow grades [1]. The initial description of this method was based on cine angiograms acquired at 30 frames per second (f/sec). In modern digital catheter labo- ratories, lower acquisition rates of 12.5, 15 and 25 f/sec are used. To be applicable in modern digital laboratories, stud- ies to determine the feasibility of producing the TIMI frame count (TFC) using lower acquisition speed and its repro- ducibility are required. We investigated this and compared our results with previously published normal values. MATERIALS AND METHODS The Local Research Ethics Committee, the Radiation Protection Adviser, and the Research and Development Committee of our institution approved the study proto- col. As part of informed consent, a full explanation of the associated risk of the extra-angiography required was given to the patient. Inclusion Criteria Participating patients were selected from those listed for elective coronary angiography. Substudy 1 The first substudy of our study population consisted of 63 consecutive patients admitted for elective coronary angiography. We measured the TIMI frame count using an acquisition speed of 12.5 and 25 f/sec in 102 coronary arteries with normal flow in these 63 patients. 1 Department of Cardiology, James Cook University Hospital, Middlesbrough, United Kingdom 2 School of Health and Social Care, University of Teesside, Middlesbrough, United Kingdom *Correspondence to: Dr. Mark A. de Belder, Department of Cardiol- ogy, James Cook University Hospital, Marton Road, Middlesbrough, TS4 3BW, United Kingdom. E-mail: mark.debelder@stees.nhs.uk Received 7 January 2004; Revision accepted 25 August 2004 DOI 10.1002/ccd.20219 Published online in Wiley InterScience (www.interscience.wiley.com). Catheterization and Cardiovascular Interventions 63:426 – 432 (2004) © 2004 Wiley-Liss, Inc.