title: Noninvasive coronary angiography with 64-section CT: effect of average heart rate and heart rate variability on image quality.
abstract: OBJECTIVE
  To evaluate prospectively the effect of average heart rate and heart rate variability on image quality at 64-section computed tomographic (CT) coronary angiography.
  
  
  METHODS
  The study protocol had local ethics committee approval; written informed consent was obtained. There were 125 patients (45 women, 80 men; mean age, 59.9 years +/- 12.9 [standard deviation]; 79 receiving beta-blockers) who underwent 64-section CT coronary angiography with retrospective electrocardiographic gating. Data sets were reconstructed in 5% steps from 20% to 80% of R-R interval. Heart rate variability was calculated as 1 standard deviation from mean rate during scanning. Two observers rated image quality of each coronary segment at least 1.5-mm diameter (1 = no motion artifacts, 5 = not evaluative). Repeated analysis of variance measurements were performed to evaluate quantitative parameters. Pearson correlation analysis was performed to compare image quality in each patient with average heart rate and heart rate variability.
  
  
  RESULTS
  Average heart rate was 63.3 beats per minute +/- 13.1, with variability of 3.2 beats per minute +/- 2.1. Diagnostic image quality (score < or = 3) was attained in 1821 of 1836 segments at the best reconstruction interval. There was no correlation between mean heart rate and image quality for all segments of the right coronary and left anterior descending arteries, but there was a significant correlation for left circumflex artery (r = 0.33, P < .05). Heart rate variability was correlated with image quality overall (r = 0.75, P < .001) and for each coronary artery. Heart rate was less variable and image quality was better (P < .05) in patients receiving beta-blockers. Best image quality was obtained in diastole with heart rate less than 80 beats per minute and in systole with faster heart rate.
  
  
  CONCLUSIONS
  Coronary angiography with 64-section CT provides diagnostic image quality within a wide range of heart rates. Reducing average heart rate and heart rate variability is beneficial for reducing artifacts.
authors.affiliation: Institute of Diagnostic Radiology, the Clinic for Cardiovascular Surgery, and the Cardiovascular Center, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Leschka
authors.forename: Simon
authors.initials: S
authors.lastname: Wildermuth
authors.forename: Thomas
authors.initials: T
authors.lastname: Boehm
authors.forename: Lotus
authors.initials: L
authors.lastname: Desbiolles
authors.forename: Lars
authors.initials: L
authors.lastname: Husmann
authors.forename: André
authors.initials: A
authors.lastname: Plass
authors.forename: Pascal
authors.initials: P
authors.lastname: Koepfli
authors.forename: Tiziano
authors.initials: T
authors.lastname: Schepis
authors.forename: Borut
authors.initials: B
authors.lastname: Marincek
authors.forename: Philipp A
authors.initials: PA
authors.lastname: Kaufmann
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*