The Potential Impact of Functional Imaging on Decision Making and Outcome in Patients Undergoing Surgical Revascularization.

OBJECTIVE: Coronary angiography (CA) remains the standard for preoperative planning for surgical revascularization. However, besides anatomical imaging, current guidelines recommend additional functional imaging before a therapy decision is made. We assess the impact of functional imaging on the strategy of coronary artery bypass grafting (CABG) with particular regards on postoperative patency and myocardial perfusion. METHODS: After CA, 55 patients (47 males/8 females; age: 65.1 ± 9.5 years) underwent perfusion cardiovascular magnetic resonance (CMR) and dual-source computed tomography (DSCT) before isolated CABG (n = 31), CABG and concomitant valve surgery (valve + CABG; n = 10) and isolated valve surgery (n = 14; control). DSCT was used for analysis of significant stenosis, CMR for myocardial-perfusion to discriminate between: no ischemia (normal), ischemia, or scar. The results, unknown to the surgeons, were compared with CA and related to the location and number of distal anastomoses. Nineteen CABG patients underwent follow-up CMR and DSCT (FU: 13 ± 3 months) to compare the preop findings with the postop outcomes. RESULTS: Thirty-nine patients either received CABG alone (n = 31) or a combined procedure (n = 10) with a total of 116 distal anastomoses. DSCT was compared with CA regarding accuracy of coronary stenosis and showed 91% sensitivity, 88% specificity, and negative/positive predictive values of 89/90%. In total, 880 myocardial segments (n = 55, 16 segments/patient) were assessed by CMR. In 17% (149/880) of segments ischemia and in 8% (74/880) scar tissue was found. Interestingly, 14% (16/116) of bypass-anastomoses were placed on non-ischemic myocardium and 3% (4/116) on scar tissue. In a subgroup of 19 patients 304 segments were evaluated. Thirty-nine percent (88/304) of all segments showed ischemia preoperatively, while 94% (83/88) of these ischemic segments did not show any ischemia postoperatively. In regard to performed anastomoses, 79% of all grafts (49/62) were optimally placed, whereas 21% (13/62) were either placed into non-ischemic myocardium or scar tissue, including 10% occluded grafts (6/62). CONCLUSION: In the whole cohort analysis, 17% of grafts were placed in regions with either no ischemia or scar tissue. The subgroup analysis revealed that 94% of all ischemic segments were successfully revascularized after CABG. Thus, functional imaging could be a promising tool in preoperative planning of revascularization strategy. Avoidance of extensive and unnecessary grafting could further optimize outcomes after CABG.

Predictors of image quality in high-pitch coronary CT angiography.

OBJECTIVE: High-pitch coronary CT angiography (CTA) shows an alternative coronary CTA protocol to retrospectively ECG-gated imaging that is associated with a significantly lower radiation exposure. Yet, the diagnostic quality of high-pitch coronary CTA cannot be sufficiently predicted on the basis of heart rate (HR) alone. Thus, we sought to prospectively identify the predictors of diagnostic high-pitch coronary CTA. SUBJECTS AND METHODS: One hundred consecutive patients (16 women, 84 men; mean age, 67 ± 10 years) without restrictions in HR frequency or variability underwent prospectively ECG-gated high-pitch coronary artery calcification (CAC) scoring and coronary CTA using dual-source 128-MDCT. High-pitch CAC was graded on the basis of motion artifacts; high-pitch coronary CTA was graded on the basis of image quality by each of two independent and blinded readers. Predictors of coronary CTA image quality were assessed by multivariate logistic regression, including body mass index, risk of coronary artery disease, Agatston score, HR frequency and variability, and motion artifacts on CAC. If high-pitch coronary CTA was nondiagnostic, the examination was repeated using a retrospectively ECG-gated coronary CTA protocol. RESULTS: HR frequency (66 ± 20 beats per minute [bpm]) and variability (12 ± 10 bpm) during high-pitch coronary CTA was not significantly different from that during high-pitch CAC. Interobserver agreement for image quality reading was good (k = 0.79) for CAC and excellent (k = 0.88) for coronary CTA. High-pitch CAC showed no motion artifacts in 1304 of 1396 segments (93.4%) in 78 of 100 patients. Diagnostic image quality of high-pitch coronary CTA was found in 1413 of 1457 segments (97%) in 82 of 100 patients. Multivariate logistic regression revealed HR frequency (odds ratio, 1.04; p < 0.05) and motion artifacts on preceding high-pitch CAC (odds ratio, 94.55; p < 0.001) as significant independent predictors of image quality of high-pitch coronary CTA. The mean effective radiation doses of high-pitch CAC and coronary CTA were 0.4 ± 0.1 mSv (0.3-0.5 mSv) and 1.0 ± 0.2 mSv (0.8-1.2 mSv; p < 0.001), respectively. CONCLUSION: HR frequency and motion artifacts on preceding high-pitch CAC represent significant independent predictors of image quality in high-pitch coronary CTA.