title: Efficacy of pre-scan beta-blockade and impact of heart rate on image quality in patients undergoing coronary multidetector computed tomography angiography.
abstract: OBJECTIVE
  While beta-blockers are routinely administered to patients prior to coronary computed tomography angiography (CTA), their effectiveness is unknown. We therefore assessed the efficacy of beta-blockade with regards to heart rate (HR) control and image quality in an unselected patient cohort.
  
  
  METHODS
  We studied 150 consecutive patients (104 men/46 female; mean age, 56+/-13 years) referred for coronary CTA. Intravenous metoprolol (5-20mg) was administered to patients with a HR >65 beats per minute (bpm). The goal HR was defined as an average HR <65 bpm without a single measurement above 68 bpm.
  
  
  RESULTS
  Overall, 45% (68/150) of patients met the HR criteria for beta-blocker administration of which 76% (52/68) received metoprolol (mean dose 12+/-10mg). Of the 52 patients who received beta-blocker versus the 98 who did not, 18 (35%) versus 62 (64%) patients achieved the goal HR, respectively. All patients who achieved the target HR had an evaluable CTA while five patients who did not achieve the target HR had at least one non-evaluable coronary artery due to motion artifact. There was also a significant reduction in any motion artifact among those who achieved the goal HR as compared to those who did not (p=0.001). Logistic regression revealed an increase in the odds of stair step artifact of 11.6% (95% CI: 2.4% decrease, 27.5% increase) per 1 bpm increase in the standard deviation of scan HR.
  
  
  CONCLUSIONS
  Overall, efficacy of beta-blocker administration to reach target HR is limited. Improvements in CT scanner temporal resolution are mandatory to achieve consistently high image quality independent of HR and beta-blocker administration.
authors.affiliation: Cardiac MR PET CT Program, Massachusetts General Hospital and Harvard Medical School, Boston MA 02114, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Shapiro
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Pena
authors.forename: John H
authors.initials: JH
authors.lastname: Nichols
authors.forename: Stewart
authors.initials: S
authors.lastname: Worrell
authors.forename: Fabian
authors.initials: F
authors.lastname: Bamberg
authors.forename: Nina
authors.initials: N
authors.lastname: Dannemann
authors.forename: Suhny
authors.initials: S
authors.lastname: Abbara
authors.forename: Ricardo C
authors.initials: RC
authors.lastname: Cury
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Brady
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage*; D016477:Artifacts; D016009:Chi-Square Distribution; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage*; D008875:Middle Aged; D014057:Tomography, X-Ray Computed; D014283:Triiodobenzoic Acids
chemical_list: D000319:Adrenergic beta-Antagonists; D003287:Contrast Media; D014283:Triiodobenzoic Acids; D008790:Metoprolol; C044834:iodixanol