Survival benefit after percutaneous treatment of chronic total coronary occlusions.

more technically challenging than twodimensional echocardiography and this is of particular importance in the CRT patient. Image acquisition requires a significant breath hold which is often difficult for the heart failure patient. Several regular cardiac beats are required and this is not always possible due to the presence of ectopy or atrial fibrillation. The large ventricular volumes seen in CRT patients means there is often incomplete capture of the dilated ventricular apex or anterior wall. Image analysis is highly dependent on image quality which is often problematic in heart failure patients. Indeed 25% of patients were excluded in the study by Krenning et al. due to poor 3D image quality. Low temporal and spatial resolution may also preclude accurate measurement of mechanical timing. Current evidence for 3D echocardiography suggests that its strength may be in the calculation of ventricular volumes and function. This technique may be of more use in the selection of patients for CRT or in gauging volumetric response when technical factors allow. The application of any new technology to patient care requires careful validation in the clinical trial setting. Three-dimensional echocardiography requires further evaluation and validation, and probably more technological advancement, before its widespread application in CRT.