Metabolic imaging Myocardial efficiency in heart failure: non invasive imaging

Any mechanical pump is far from efficient. Only a fraction of its input energy is ultimately converted to external work. In the case of the heart, this fraction is approximately 25%, and is defined as mechanical efficiency. Heart failure as a result of dilated cardiomyopathy is characterized by a reduction in efficiency, the extent of which serves as an important prognostic marker. Despite its relevance in studying disease and monitoring interventions, mechanical efficiency is not routinely determined, as it requires a highly invasive procedure. In recent years, however, advances in imaging techniques have made possible the non invasive assessment of this parameter. In this review, we discuss these currently available techniques, including their pitfalls, and place into clinical perspective the studies in which they have been applied. Heart Metab. 2008;39:14–19.