title: Prospective and retrospective ECG-gating for CT coronary angiography perform similarly accurate at low heart rates.
abstract: OBJECTIVE
  To compare, in patients with suspicion of coronary artery disease (CAD) and low heart rates, image quality, diagnostic performance, and radiation dose values of prospectively and retrospectively electrocardiography (ECG)-gated dual-source computed tomography coronary angiography (CTCA) for the diagnosis of significant coronary stenoses.
  
  
  METHODS
  Two-hundred consecutive patients with heart rates ≤70 bpm were retrospectively enrolled; 100 patients undergoing prospectively ECG-gated CTCA (group 1) and 100 patients undergoing retrospectively-gated CTCA (group 2). Coronary artery segments were assessed for image quality and significant luminal diameter narrowing. Sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), and accuracy of both CTCA groups were determined using conventional catheter angiography (CCA) as reference standard. Radiation dose values were calculated.
  
  
  RESULTS
  Both groups were comparable regarding gender, body weight, cardiovascular risk profile, severity of CAD, mean heart rate, heart rate variability, and Agatston score (all p>0.05). There was no significant difference in the rate of non-assessable coronary segments between group 1 (1.6%, 24/1404) and group 2 (1.4%, 19/1385; p=0.77); non-diagnostic image quality was significantly (p<0.001) more often attributed to stair step artifacts in group 1. Segment-based sensitivity, specificity, PPV, NPV, and accuracy were 98%, 98%, 88%, 100%, and 100% among group 1; 96%, 99%, 90%, 100%, and 98% among group 2, respectively. Parameters of diagnostic performance were similar (all p>0.05). Mean effective radiation dose of prospectively ECG-gated CTCA (2.2±0.4 mSv) was significantly (p<0.0001) smaller than that of retrospectively ECG-gated CTCA (8.1±0.6 mSv).
  
  
  CONCLUSIONS
  Prospectively ECG-gated CTCA yields similar image quality, performs as accurately as retrospectively ECG-gated CTCA in patients having heart rates ≤70 bpm while being associated with a lower mean effective radiation dose.
authors.affiliation: Institute of Diagnostic Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland. paul.stolzmann@usz.ch
authors.forename: Paul
authors.initials: P
authors.lastname: Stolzmann
authors.forename: Robert
authors.initials: R
authors.lastname: Goetti
authors.forename: Stephan
authors.initials: S
authors.lastname: Baumueller
authors.forename: André
authors.initials: A
authors.lastname: Plass
authors.forename: Volkmar
authors.initials: V
authors.lastname: Falk
authors.forename: Hans
authors.initials: H
authors.lastname: Scheffel
authors.forename: Gudrun
authors.initials: G
authors.lastname: Feuchtner
authors.forename: Borut
authors.initials: B
authors.lastname: Marincek
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.forename: Sebastian
authors.initials: S
authors.lastname: Leschka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D016009:Chi-Square Distribution; D003287:Contrast Media; D023921:Coronary Stenosis / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide