Left atrial volume: comparison of 2D and 3D transthoracic echocardiography with ECG-gated CT angiography.

RATIONALE AND OBJECTIVES: Left atrial volume (LAV) measurement by conventional two-dimensional (2D) transthoracic echocardiography (TTE) may be limited by the geometric model, by suboptimal definition of left atrial endocardium, or by chamber foreshortening. Three-dimensional (3D) TTE is posited to eliminate chamber foreshortening, and LAV measurement by 3D TTE should be more reflective of true LAV. The aim of this study was to compare conventional 2D TTE and newer 3D TTE for measurements of LAV to multidetector computed tomographic (MDCT) measurements using automated chamber reconstruction (ACR). MATERIALS AND METHODS: Twenty-two subjects consented to undergo 2D TTE and 3D TTE immediately prior to or following coronary computed tomographic angiography. LAV was calculated from 2D TTE using the area-length method (ALM) and from 3D TTE with the ALM as well as with a 3D model. Electrocardiographically gated coronary computed tomographic angiography was performed in helical mode. LAV was measured using the ALM as well as ACR. RESULTS: LAV was significantly smaller by 2D TTE (80 ± 21 mL) and 3D-TTE (90 ± 24 mL with the ALM, 61 ± 16 mL with the 3D model) compared to MDCT ACR (120 ± 30 mL) (P \u3c .01). Correlation between MDCT ALM and MDCT ACR was excellent (mean Δ = -1.4 ± 14 mL, r = 0.91). Correlation with MDCT ACR was no better for 3D TTE (r = 0.80) than for 2D TTE (r = 0.80). CONCLUSIONS: LAV is underestimated by both 2D TTE and 3D TTE relative to coronary computed tomographic angiography. Excellent agreement between the ALM and ACR with MDCT imaging suggests that the geometric model plays a negligible role in the underestimation of LAV. Underestimation of LAV by echocardiography is likely related to suboptimal definition of left atrial contour

Decision analytic model for evaluation of suspected coronary disease with stress testing and coronary CT angiography.

RATIONALE AND OBJECTIVES: The aim of this study was to apply a decision analytic model for the evaluation of coronary artery disease (CAD) to define the optimal utilization of coronary computed tomographic angiography (cCTA) and stress testing. MATERIALS AND METHODS: The model tested in this study assumes that CAD is evaluated with a stress test and/or cCTA and that a patient with positive evaluation results undergoes cardiac catheterization. On the basis of values of sensitivity, specificity, and radiation dose from the published literature and test costs from the Medicare fee schedule, a decision tree model was constructed as a function of disease prevalence. RESULTS: The false-negative rate is lowest when cCTA is used as an isolated test. The false-positive rate is minimized when cCTA is used in combination with stress echocardiography. Effective radiation is minimized by use of stress electrocardiography or stress echocardiography alone or prior to cCTA. When the pretest probability of CAD is low, a strategy that uses stress echocardiography followed by cCTA minimizes the false-positive rate and effective radiation exposure, with relatively low imaging costs and with a false-negative rate only slightly higher than a strategy including stress myocardial scintigraphy. As the pretest probability of CAD increases above 20%, the false-negative rate of stress echocardiography followed by cCTA increases by \u3e5% relative to cCTA alone. CONCLUSION: Effective radiation dose and imaging costs for the workup of CAD may be minimized by an appropriate combination of stress testing and cCTA. A strategy that uses stress echocardiography followed by cCTA is most appropriate for the evaluation of low-risk patients with CAD with a pretest probability \u3c 20%, while cCTA alone may be more appropriate in intermediate-risk patients