Cardiac radionuclide imaging to assess patients with heart failure.

Heart failure (HF) is a major problem, with a high prevalence, morbidity, mortality, and cost, and is expected to become more widespread. Radionuclide imaging currently plays an important role in evaluating these patients, with much potential for increased utility. Myocardial perfusion imaging (MPI) with radiotracers is commonly used to differentiate an ischemic from a nonischemic etiology of HF and cardiomyopathy. In some instances, MPI effectively distinguishes among these, but often, standard MPI is deficient in that a nonischemic cardiomyopathy can have focal defects in tracer uptake and coronary artery disease with global balanced ischemia can result in a normal-appearing perfusion pattern. Developments in measuring quantitative blood flow promise to provide a more accurate determination of HF etiology. If coronary artery disease is established, MPI has long established use for assessment of myocardial viability and identification of patients likely to benefit from revascularization. Although a recent multicenter trial substudy has questioned the benefits of viability imaging, specific limitations of this study must be balanced against previously demonstrated utility. At the same time, viability imaging may need to be directed more skillfully toward carefully selected patients. In patients with HF who are not candidates for revascularization, myocardial remodeling often leads to poor patient outcome. Newer nuclear analyses of myocardial shape and of dyssynchronous contraction or relaxation can risk stratify patients and may help guide therapy. Investigative molecular imaging techniques promise to better understand underlying pathophysiology and guide therapy on an individual basis. Finally, recent approval of a tracer for cardiac autonomic innervation imaging should greatly expand the use of radionuclide imaging in HF, potentially guiding proper use of life saving but expensive and high-risk mechanical therapies. Given the molecular basis of much of the pathophysiology of HF, the contribution of cardiac radionuclide imaging to improve patient care should increase.