A combination of anatomical and functional evaluations improves the prediction of cardiac event in patients with coronary artery bypass.
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).


METHODS
A retrospective, observational, single centre study.


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


METHODS
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.
Department of Cardiology, Fujita Health University, Toyoake, Japan.
Hideki
H
Kawai
Masayoshi
M
Sarai
Sadako
S
Motoyama
Hajime
H
Ito
Kayoko
K
Takada
Hiroto
H
Harigaya
Hiroshi
H
Takahashi
Shuji
S
Hashimoto
Yasushi
Y
Takagi
Motomi
M
Ando
Hirofumi
H
Anno
Junichi
J
Ishii
Toyoaki
T
Murohara
Yukio
Y
Ozaki