We have previously shown in a double-blind crossover study that digitalis could be discontinued for three months without adverse clinical effect and only minor changes in cardiac size and function in 30 subjects with stable congestive heart failure (CHF) and sinus rhythm. Long-term follow-up of these patients verified this favorable early response to digitalis withdrawal. We have initiated a new study to investigate the effects of digitalis on aerobic performance and cardiac function during exercise (measured via gated blood pool scan) and its effects on cardiac rhythm in a new group of patients with chronic CHF and sinus rhythm. Our group has helped to develop a questionnaire in conjunction with experts in cardiology at different universities. This questionnaire has been implimented with the help of the American Heart Association to sample representative groups of academic and practicing physicians in their current use and understanding of the effectiveness and toxicity of digitalis glycosides. The results will be important in identifying areas of consensus and areas in which major uncertainties exist; the important categories within the latter will serve as a basis for future research projects in which NIH may find a direct role.