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A combination of anatomical and functional evaluations improves the prediction of cardiac event in patients with coronary artery bypass
  1. Hideki Kawai1,
  2. Masayoshi Sarai1,
  3. Sadako Motoyama1,
  4. Hajime Ito1,
  5. Kayoko Takada1,
  6. Hiroto Harigaya1,
  7. Hiroshi Takahashi2,
  8. Shuji Hashimoto3,
  9. Yasushi Takagi4,
  10. Motomi Ando4,
  11. Hirofumi Anno5,
  12. Junichi Ishii1,
  13. Toyoaki Murohara6,
  14. Yukio Ozaki1
  1. 1Department of Cardiology, Fujita Health University, Toyoake, Japan
  2. 2Departments of Medical Statistics, Fujita Health University, Toyoake, Japan
  3. 3Department of Hygiene, Fujita Health University, Toyoake, Japan
  4. 4Department of Cardiovascular Surgery, Fujita Health University, Toyoake, Japan
  5. 5Departments of Radiology, Fujita Health University, Toyoake, Japan
  6. 6Department of Cardiology, Nagoya University Graduate School of Medicine, Fujita Health University, Toyoake, Japan
  1. Correspondence to Dr Hideki Kawai; hkawai{at}


Objective To study the usefulness of combined risk stratification of coronary CT angiography (CTA) and myocardial perfusion imaging (MPI) in patients with previous coronary-artery-bypass grafting (CABG).

Design A retrospective, observational, single centre study.

Setting and patients 204 patients (84.3% men, mean age 68.7±7.6) undergoing CTA and MPI.

Main outcome measures CTA defined unprotected coronary territories (UCT; 0, 1, 2 or 3) by evaluating the number of significant stenoses which were defined as the left main trunk ≥50% diameter stenosis, other native vessel stenosis ≥70% or graft stenosis ≥70%. Using a cut-off value with receiver-operating characteristics analysis, all patients were divided into four groups: group A (UCT=0, summed stress score (SSS)<4), group B (UCT≥1, SSS<4), group C (UCT=0, SSS≥4) and group D (UCT≥1, SSS≥4).

Results Cardiac events, as a composite end point including cardiac death, non-fatal myocardial infarction, unstable angina requiring revascularisation and heart-failure hospitalisation, were observed in 27 patients for a median follow-up of 27.5 months. The annual event rates were 1.1%, 2%, 5.7% and 12.9% of patients in groups A, B, C and D, respectively (log rank p value <0.0001). Adding UCT or SSS to a model with significant clinical factors including left ventricular ejection fraction, time since CABG and Euro SCORE II improved the prediction of events, while adding UCT and SSS to the model improved it greatly with increasing C-index, net reclassification improvement and integrated discrimination improvement.

Conclusions The combination of anatomical and functional evaluations non-invasively enhances the predictive accuracy of cardiac events in patients with CABG.

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