title: Low-dose computed tomography coronary angiography with prospective electrocardiogram triggering: feasibility in a large population.
abstract: OBJECTIVE
  We sought to assess the feasibility of prospective electrocardiogram triggering for achieving low-dose computed tomography coronary angiography (CTCA) in a large population.
  
  
  BACKGROUND
  Prospective electrocardiogram triggering dramatically reduces radiation exposure for CTCA but requires heart rate (HR) control to obtain diagnostic image quality. Its feasibility in daily clinical routine has therefore remained to be elucidated.
  
  
  METHODS
  We evaluated 612 patients consecutively referred for CTCA by 64-slice computed tomography. Intravenous metoprolol (2 to 30 mg) was administered if necessary to achieve a target HR below 65 beats/min. Image quality was assessed on a semiquantitative 4-point scale for each coronary segment.
  
  
  RESULTS
  Forty-six (7.5%) patients were deemed ineligible due to irregular heart rhythm (n = 19), insufficient response to metoprolol (n = 21), renal insufficiency (n = 3), or inability to follow breath-hold commands (n = 3). Mean effective radiation dose was 1.8 ± 0.6 mSv with a diagnostic image quality in 96.2% of segments. Finally, low-dose CTCA allowed a firm diagnosis with regard to the presence or absence of coronary artery disease in 527 (86.1%) patients. Intravenous metoprolol to achieve an HR below 65 beats/min was used in 64.4% of patients. Incidence of nondiagnostic segments was inversely related to HR (r = -0.809, p < 0.001). Below an HR cutoff of 62 beats/min, only 1.2% of coronary segments were nondiagnostic.
  
  
  CONCLUSIONS
  Low-dose CTCA by electrocardiogram triggering is feasible in the vast majority of an every-day population. However, HR control is crucial, as an HR below 62 beats/min favors diagnostic image quality.
authors.affiliation: University Hospital Zurich, Switzerland.
authors.forename: Ronny R
authors.initials: RR
authors.lastname: Buechel
authors.forename: Lars
authors.initials: L
authors.lastname: Husmann
authors.forename: Bernhard A
authors.initials: BA
authors.lastname: Herzog
authors.forename: Aju P
authors.initials: AP
authors.lastname: Pazhenkottil
authors.forename: Rene
authors.initials: R
authors.lastname: Nkoulou
authors.forename: Jelena R
authors.initials: JR
authors.lastname: Ghadri
authors.forename: Valerie
authors.initials: V
authors.lastname: Treyer
authors.forename: Patrick
authors.initials: P
authors.lastname: von Schulthess
authors.forename: Philipp A
authors.initials: PA
authors.lastname: Kaufmann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult