Estudo de parâmetros ecodopplercardiográficos de patência do enxerto composto de artéria torácica interna esquerda

Abstract

Composite grafts with left internal thoraic artery (LITA) has incresed its applicability in Coronary Artery Bypass Surgery (CAGB). Confirmation of patency of the LITA graft is the cornerstone of Miocardial Revascularization. The best measure of patency calculated by Doppler echocardiogram (Doppler) is the diastolic fraction (DF) ≥ 0.5. The aim of this study was to establish Doppler echocardiographic parameters which could suggest the presence of a composite graft of LITA, when it revascularizes the anterior interventricular artery (AIA) and another branch of the left coronary artery system. The endpoint of this study was to define sensitivity and specificity considering three variables: ratio of peak velocity in diastole over the systolic peak velocity (DPV / SPV), the mean velocity-time integral in diastole (VTID) and FD of the composite graft patency using FD ≥ 0.5 as the reference standard. The study was conducted according to a design in two stages. It was defined a control group and study group. In the control group, all patients had graft patencies confirmed by coronary angiography (CINE) and the variables DPV / SPV,VTID and DF measured. So, we use this data to establish cutoff points for these variables , based on the calculation of sensitivity and specificity using the ROC curve (Receiverv Operation Characteristic) in order to differentiate composite from simple graft when ATIE only revascularizes the AIA. These cutoff points were applied in patients with composite graft group study. We built a 2x2 contingency table to calculate sensitivity and specificity, considering the indicator of patency a DF ≥ 0.5. In the control group, we observed statistically significant differences in the analysis of the three variables in differentiating simple from composite grafts. The parameters of composite graft patency established by the study group were DPV / SPV ≥ 0.71,VTID ≥ 0.09 and FD ≥ 0.58. The specificity for all these variables was 100%. The sensitivity was 40% for DPV / SPV ≥ 0.71, ≥ 36.4% for VTId≥ 0.09 and 68% for FD ≥ 0.58. We conclude that values greater than or equal to those established for each variable represents a likely indicator of graft patency compound. Values below the established are not conclusive to exclude composite grafts due to a large proportion off alse negatives.