Age- and gender-specific differences in the prognostic value of CT coronary angiography

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    Age- and gender-specific differences in the prognosticvalue of CT coronary angiography

    Kai Hang Yiu,1,2 Fleur R de Graaf,1 Joanne D Schuijf,1 Jacob M van Werkhoven,1,2

    Nina Ajmone Marsan,1 Caroline E Veltman,1 Albert de Roos,3 Aju Pazhenkottil,4

    Lucia J Kroft,3 Eric Boersma,5 Bernhard Herzog,4 Melissa Leung,6 Erica Maffei,7

    Dominic Y Leung,6 Philipp A Kaufmann,4,8 Filippo Cademartiri,7 Jeroen J Bax,1

    J Wouter Jukema1,2

    ABSTRACTObjective To evaluate the potential age- and gender-specific differences in the incidence and prognostic valueof coronary artery disease (CAD) in patients undergoingCT coronary angiography (CTA).Design and patients In this multicentre prospectiveregistry study, 2432 patients (mean age 57612, 56%male) underwent CTA for suspected CAD. Patients werestratified into four groups according to age

  • infarction. Moreover, a total of 42 uninterpretable scans wereexcluded from the analysis (33 owing to motion artefact/poorscan quality, eight owing to high coronary calcification leadingto blooming artefact and one owing to non-diagnostic CTAstent image quality). Accordingly, 2432 patients were includedin the final analysis. The pre-test likelihood of obstructive CADwas evaluated using Diamond and Forrester s criteria.10 Patientswere entered prospectively into the departmental patientinformation system and retrospectively analysed. This studywas approved by the local ethics committees in all participatingcentres and all patients provided informed consent.

    CT coronary angiography protocolExaminations were performed using one of the following scanners:(1) 320-row CTA scanner (Aquilion ONE, Toshiba MedicalSystems, Otawara, Japan) in 97 (4%) patients; (2) 64-row CTAscanner (Lightspeed VR 64, General Electrics (GE), Milwaukee,Michigan, USA or Aquillion64, Toshiba Medical Systems, TokyoJapan or Sensation64, Siemens, Forchheim, Germany) in 2335(96%) patients. Patients heart rate and blood pressure weremonitored before each CTA scan. In the absence of contraindica-tions, 44% patients with a heart rate >65 beats/min were givenb-blocking drugs (50e100 mg metoprolol, orally or 5e10 mgmetoprolol, intravenously) for heart rate optimisation. A descrip-tion of all scan parameters has been published previously.6 11e13

    In brief, all images were acquired during a single inspiratory breath-hold of maximally 12 s. For 320-row CTA, the ECG was registeredsimultaneously for prospective triggering of the data.6 The entireheart was imaged in a single heart beat and maximal tube currentwas attained during 75% of the R-R interval in patients with stableheart rate 65 bpm.In addition, a collimation of 32030.5 mm was used. Additionalscan parameters were as follows: 350 ms gantry rotation time,120e135 kV tube voltage and 400e580 mA (depending on bodymass index and thoracic geometry). For 64-row CTA, a helical-scanning technique was used as previously described, usinga collimation of 6430.5 mm.11e14 Specifically, retrospective gatingof the data was registered by simultaneous ECGmonitoring. Whenprospective triggering was performed, a small acquisition windowduring mid-diastolic phase of the R-R cycle was used (ie, 70e80%in the case of low heart rate).14 Retrospective gating of the datawas registered by the simultaneous ECG monitoring, and a colli-mation of 6430.5 mm was used. Additional scan parameters were400 ms or 500 ms gantry rotation time depending on the cardiacfrequency, 120 kV tube voltage and 300e350 mA (depending onbody mass index and thoracic geometry).

    The estimated mean radiation dose for retrospective gatingwith 64-slice CT is 18.0 mSv (range 6.8e45.5 mSv).15 Forprospective triggering with 64-slice CTA the estimated meanradiation dose is 2.1 mSv (range 1.1e3.0 mSv).14 For prospectivetriggering using 320-row CTA, the estimated mean radiationdose is 3.9 mSv (range 2.7e26.2 mSv).6

    Data analysisPost-processing of the CTA was performed on dedicated work-stations (Vitrea2, Vital Images, Minneapolis, Minnesota, USA orAdvantage, GE Healthcare, Waukesha, Wisconsin, USA or SyngoInSpace4D Application, Siemens, Munich, Germany orAquarius, TeraRecon, San Mateo, California, USA). Coronaryanatomy was assessed using a standardised method by dividingthe coronary arteries into 17 segments according to the modifiedAmerican Heart Association classification.16 CTA results were

    defined as normal CTA (no identifiable plaque or minimal wallirregularities), non-obstructive CAD (

  • including non-fatal myocardial infarction in 34 cases and CVSmortality in 25 cases. No difference in the occurrence of thecomposite end point was noted between male (aged
  • of age. Similarly, CTA was a strong predictor of CVS events infemale patients aged $60 years. In contrast, however, CTAprovided limited prognostic value in female patients aged
  • investigation demonstrated that the presence of obstructiveCAD had significant prognostic value for both genders. Incontrast to their study, our study showed that non-obstructiveCAD was predictive for future CVS events in female patientsand also in male patients. Conceivably, non-obstructive plaquemay play a more important role in female patients, whereas itspredictive value may be less in male patients. Accordingly, thediscrepancy between the study by Shaw et al and ours may beexplained by the larger number of patients enrolled in our study.As compared with female patients, male patients had a largerseparation of survival curves between non-obstructive andobstructive CAD in comparison with normal CTA. This obser-vation could be partially explained by the altered coronaryreactivity that frequently occurred in women.27 In addition,a recent study by Pepine et al showed that coronary microvas-cular reactivity to adenosine provided prognostic value overangiographic CAD severity in female patients.28 Nevertheless,the underlying mechanism of non-obstructive CAD leading tomore adverse outcome in female patients than in male patientswith non-obstructive CAD will require further study.

    In concordance with data from the National Institutes ofHealth, National Heart, Lung and Blood Institute, a lowannualised CVS event rate was seen in female patients aged

  • current guideline for the use of CTA is based on expertconsensus, and thus large-scale randomised studies are needed toevaluate the clinical effectiveness guided by the test results.34

    Multivariate adjustment for the independent prognostic role ofCTA results was not performed owing to a lack of statisticalpower as a result of the limited cardiovascular events in eachsubgroup after age and gender stratification. Finally, it isimportant to realise that despite the reduced radiation burdendue to prospective ECG triggering, the risk of radiation exposureassociated with CTA should not be disregarded, particularly inyounger women.

    CONCLUSIONThis study confirmed that male patients had a significantlyhigher frequency of obstructive CAD on CTA than femalepatients. Moreover, the presence of both non-obstructive CADand obstructive CAD on CTA was significantly predictive ofCVS events in both genders. Importantly, after age stratification,CTA findings were shown to be of limited predictive value infemale patients aged

  • doi: 10.1136/heartjnl-2011-300038 2012 98: 232-237 originally published online September 13, 2011Heart

    Kai Hang Yiu, Fleur R de Graaf, Joanne D Schuijf, et al. angiographyprognostic value of CT coronary Age- and gender-specific differences in the information and services can be found at:

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