Clinical trials of diuretic therapy in heart failure: research directions and clinical considerations.

Diuretic drugs have historically been developed for the treatment of sodium and water retention in edematous disorders. The latter have traditionally been an amalgam of congestive heart failure, nephrotic syndrome, cirrhosis and chronic renal failure. With a > 50-year tradition of this approach to development, diuretic drugs have not been evaluated specifically for their safety and efficacy profile in patients with congestive heart failure. Yet, they are the most frequently prescribed drug class for this disorder. Furthermore, they remain the only drug class in congestive heart failure not subjected to large scale clinical trials. Sodium and water retention within this group of patients is related primarily to functional rather than to structural renal abnormalities. The reduction of glomerular filtration rate, increase in aldosterone secretion and abnormal profile of atrial natriuretic factor, all produce sodium retention and can be related to the severity of heart failure. Diuretic drugs have not been scrutinized in a manner similar to that of other drugs for the management of heart failure. Controversy persists regarding direct vascular effects, objective end points of assessment and the magnitude of adverse effects such as activation of neurohormonal pathways. These issues may be addressed by the establishment of reasonable objective end points, better stratification of patients in clinical trials and prospective trials in large clinical series. Even mortality studies should be considered.