文摘
Objectives: This study sought to evaluate the long‐term prognostic significance of stress–redistribution–reinjection Tl‐201 imaging in patients with severe left ventricular (LV) dysfunction and coronary artery bypass surgery. Background: Preoperative stress–redistribution–reinjection Tl‐201 imaging detects viable but asynergic segments which show functional improvement postoperatively and is considered as a valuable noninvasive method in selection of patients with severe LV dysfunction for revascularization. The long‐term prognostic value of the reinjection technique remains unclear. Methods: Fifty‐two patients with severe LV dysfunction (mean ejection fraction (EF) 0.32 ± 0.03) who underwent coronary artery bypass surgery in 1993–1994 were included in the study. Patients had follow‐up 49 ± 12 months. LV function was assessed by two‐dimensional echocardiography. Perfusion was assessed by Tl‐201 SPECT imaging and was graded on a four‐point scale (0 = normal, 3 = absent uptake) using the 20 segment model. Perfusion index was derived by adding the score of all segments and dividing these by 20. Patients were divided into two groups. Group A comprised patients with seven and more dysfunctional viable myocardial segments. Group B included patients with less than seven dysfunctional but viable segments. Results: Mean EF increased from 0.32 ± 0.03 to 0.46 ± 0.04. Mean perfusion index did not show a significant difference as a whole during follow‐up compared to the early postoperative values (0.9 ± 0.4 and 1.1 ± 0.4, p = NS). When adequacy of revascularization was considered, the predictive value of a positive preoperative viability test for functional improvement was 82%. Nineteen cardiac events occurred in group B patients and six in group A patients: six deaths (four from cardiac and two from noncardiac causes), 13 myocardial infarctions (MI). Multivariate Cox survival analysis identified the number of viable segments detected preoperatively (&khgr; = 7.2, p = 0.002), postoperative improvement in Tl‐uptake (&khgr; = 6.6, p = 0.01) and functional improvement (&khgr; = 5.3, p = 0.03) postoperatively as independent predictors of cardiac events. Preoperative EF and functional capacity were not associated with cardiac events in long‐term prognosis. Conclusion: These data suggest that preoperative stress–redistribution–reinjection Tl‐201 imaging, specifically the number of viable segments detected preoperatively and postoperative improvement in Tl‐201 uptake provide important long‐term prognostic information in patients with severe LV dysfunction who had coronary artery bypass surgery.
