Impact of preoperative positron emission tomography in patients with severely impaired LV-function undergoing surgical revascularization

Abstract

In patients with ischemic cardiomyopathy, coronary artery bypass grafting (CABG) offers an important therapeutic option but is still associated with high perioperative mortality. Although previous studies suggest a benefit from revascularization for patients with defined viability by a non-invasive technique, the role of viability assessment to determine suitability for revascularization in patients with ischemic cardiomyopathy has not yet been defined. This study evaluates the hypothesis that the use of PET imaging in the decision-making process for CABG will improve postoperative patient survival. We reviewed 476 patients with ischemic cardiomyopathy (LV ejection fraction <or=0.35) who were considered candidates for CABG between 1994 and 2004 on the basis of clinical presentation and angiographic data. In a Standard Care Group, 298 patients underwent CABG. In a second PET-assisted management group of 178 patients, 152 patients underwent CABG (PET-CABG) and 26 patients were excluded from CABG because of lack of viability (PET-Alternatives). Primary endpoint was postoperative survival. There were two in hospital deaths in the PET-CABG (1.3%) and 30 (10.1%) in the Standard Care Group (P = 0.018). The survival rate after 1, 5 and 9.3 years was 92.0, 73.3 and 54.2% in the PET-CABG and 88.9, 62.2 and 35.5% in the Standard Care Group, respectively (P = 0.005). Cox-regression analysis revealed a significant influence on long-term survival of patient selection by viability assessment via PET (P = 0.008), of LV-function (P = 0.017), and age >70 (P = 0.016). Preoperative assessment of myocardial viability via PET identifies patients, who will benefit most from CABG.

Fig. 1

476 candidates for CABG 1994-2004. Patients were selected for CABG on the basis of clinical presentation and angiographic data (n = 298, Standard Care Group) or on the basis of an additional assessment of the extent of viable tissue by PET (n = 178). 152 patients of the latter group underwent CABG (PET-CABG) and 26 patients were excluded from CABG because of lack of viability (PET-Alternatives) and either underwent heart transplantation (n = 8) or received medical treatment only (n = 18)

Fig. 2

PET-Studies and Viability Assessment. Attenuation-corrected transaxial PET images were generated from N-13 ammonia and F-18 FDG data. The images were reoriented perpendicular to the long axis of the left ventricle, after which volume-weighted polar maps were calculated from circumferential profiles of the maximal myocardial activity

Fig. 3

Cumulative survival after CABG