title: Effect of potential confounding factors on the thrombolysis in myocardial infarction (TIMI) trial frame count and its reproducibility.
abstract: BACKGROUND
  The potential factors that introduce variability into TIMI frame count (TFC) have not been systematically investigated. The goal of this study was to determine if nitrate use, dye injection rate, catheter size, the phase of the cardiac cycle in which dye is injected, or heart rate affect the TFC and to investigate the reproducibility of the TFC.
  
  
  RESULTS
  The dye injection rate was increased 1 mL/s, and angiography was repeated. A coronary angiogram was taken first with an 8F catheter and then with a 6F catheter. After taking angiograms, intracoronary nitrate was given to the patient, and the second angiography was performed. Basal heart rate was increased 20 beats/min, and angiography was repeated. Dye injection was performed at the beginning of systole and diastole. The TFC was not significantly changed by increasing the dye injection rate (P=0.467) or by changing catheter size (P=0.693). Nitrate administration significantly increased the TFC from 26.4+/-11.9 to 32.8+/-13.3 frames (P<0.001). Dye injection at the beginning of diastole significantly decreased the TFC from 30.1+/-8.8 to 24.4+/-7.9 frames (P<0.001) for the left coronary artery and from 24.16+/-4.49 to 21. 24+/-4.45 frames (P<0.001) for the right coronary artery. Increasing heart rate significantly decreased the TFC from 30.4+/-6.1 to 25. 3+/-7.2 frames (P<0.001). Intraobserver and interobserver reproducibility of the TFC was good (mean difference, 1.33+/-1.24 and 2.57+/-1.72 frames, respectively).
  
  
  CONCLUSIONS
  Nitrate use, heart rate, and the phase of the cardiac cycle in which dye is injected had significant effects on the TFC. Therefore, studies comparing TFC need to consider these factors, and the use of nitrates should be either standardized or randomized.
authors.affiliation: Department of Cardiology, Erciyes University School of Medicine, Kayseri, Turkey. abacia@hotmail.com
authors.forename: A
authors.initials: A
authors.lastname: Abaci
authors.forename: A
authors.initials: A
authors.lastname: Oguzhan
authors.forename: N K
authors.initials: NK
authors.lastname: Eryol
authors.forename: A
authors.initials: A
authors.lastname: Ergin
mesh_terms: D000328:Adult; D000368:Aged; D006328:Cardiac Catheterization / Q000295:instrumentation; D002317:Cardiovascular Agents / Q000494:pharmacology; D002932:Cineangiography; D015897:Comorbidity; D003287:Contrast Media / Q000008:administration & dosage / Q000494:pharmacology; D017023:Coronary Angiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D008140:Lorazepam / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000188:drug therapy*; D005996:Nitroglycerin / Q000494:pharmacology; D015588:Observer Variation; D015635:Radionuclide Ventriculography; D015203:Reproducibility of Results; D012107:Research Design; D015912:Thrombolytic Therapy
chemical_list: D002317:Cardiovascular Agents; D003287:Contrast Media; D006993:Hypnotics and Sedatives; D005996:Nitroglycerin; D008140:Lorazepam