Does Doppler echography have a diagnostic role in patency assessment of internal thoracic artery grafts?

Abstract

The amount of literature published over the past decade comparing coronary angiography with transthoracic Doppler echocardiography assessment of internal thoracic artery graft patency after CABG is substantial. There has been no review of the available literature, and conflicting reports of diagnostic accuracy have prevented routine use of transthoracic Doppler in graft patency assessment. Thus, this article reviews the available literature on diagnostic accuracy of transthoracic Doppler echocardiography of coronary bypass grafts. Relevant studies were identified and meta-analysis of diagnostic accuracy was performed. Study quality was assessed. Quantitative data synthesis included calculation of sensitivity, specificity, summary receiver operating characteristic curve analysis, pooled analysis and meta-regression of accuracy against study quality, publication date, angina, probe frequency and diagnostic criteria. Twenty studies of 929 patients produced 26 results included for analysis. Grafts were not visualized in 93 (10%) patients. Pooled sensitivity (85%) and specificity (94%) and diagnostic odds ratio (100.7) were high. SROC analysis showed an area under the curve of 0.96. Heterogeneity of results was due to variations in diagnostic criteria and study size. Subgroup analysis showed best performance in patients with postoperative angina (p = 0.014). Study quality did not affect results. Diastolic fraction less than 0.5 (sensitivity 89%, specificity 94%) was shown to be the best criterion for prediction of stenosis. Performance was lower using peak diastolic to systolic velocity ratio less than 1 (sensitivity 85%, specificity 86%). Transthoracic Doppler echography is effective in first-line assessment of left internal thoracic artery graft patency. It shows high specificity, prevents invasive investigations and improves in patients with postoperative angina. TDE is best used in combination with other non-invasive tests due to its inability to visualize the graft. The potential for use in postoperative coronary bypass patients is high.

Diagnostic accuracy of Doppler ultrasonography for assessment of internal thoracic artery graft patency

“…In addition, Ichikawa and colleagues (11) stated that these graft flow dynamics were unchanged even after 10 years and this hemodynamic characteristic may be one of the factors related to superior long-term patency. In a review, Jones et al (20) reported that transthoracic Doppler USG is effective in first-line assessment of LITA graft patency. It shows high specificity, prevents invasive investigations and improves in patients with postoperative angina.…”

“…A poor LAD target vessel quality, competitive flow from a partially occluded proximal LAD, residual LITA side branches and the contractility and viability of the perfused myocardium can affect the Doppler flow values also. All these factors could be associated with diminished diastolic flow of the LITA-LAD bypass (19)(20)(21). The DSVR is used because this ratio is independent of the ultrasound beam angle of incidence that effects Doppler calculations (16).…”

Evaluation of ITA Graft Function Using CT Angiography

“…10,11) Many reports suggest the usefulness and feasibility of PDE in assessing ITA graft function. [5][6][7] Those many reports recommended adopting mean flow, diastolic flow, VTI or DF of ITA graft to assess its function, which we adopted in this study, as well. In this study, the heart rate of subjects during the PDE examination ranged from 52 to 97 beats per minute, not only for VTI, which represented only one cardiac cycle, but also for VTI x HR, which was closer to the cardiac output and seemed to be a meaningful variable of PDE.…”

“…[5][6][7] However, it is hard to obtain structural information of ITA grafts using PDE. If there is a method to assess ITA graft function by CT angiography, structural and functional information of ITA grafts can be obtained safely at the same time, which may be an ideal examination.…”

Doppler echocardiographic criteria in patency assessment of composite grafts from left internal thoracic artery

“…The diastolic fraction calculated using the velocity integral has shown a good correlation with cardiac catheterization results. A DF value lower than 0.5 is predictive of graft stenosis [16,22].…”