Digitalis Investigation Group (DIG)

BACKGROUND:

Despite widespread use of digitalis and its availability for nearly two centuries, uncertainty surrounded the appropriateness of its role and value in treating congestive heart failure patients in sinus rhythm. The study was a multicenter collaborative effort with the Department of Veteran Affairs Cooperative Studies Program which provided support for a data coordinating center and a pharmacy coordinating center.

DESIGN NARRATIVE:

Randomized, double-blind, simple, multicenter, international trial with 186 centers in the United States and 116 in Canada. In the main trial, patients with left ventricular ejection fractions of 0.45 or less were randomly assigned to digoxin (3397 patients) or placebo (3403 patients) in addition to diuretics and ACE inhibitors. In an ancillary trial of patients with ejection fractions greater than 0.45, 492 patients were randomly assigned to digoxin and 496 to placebo. Patients were recruited over a three-year period at the 302 centers and followed for a minimum of two years. Patient enrollment began in February 1991 and ended in September 1993. Follow-up ended in December 1995. The main results paper was published in 1997.

Three substudies were conducted. The quality of life/6-minute walk test substudy determined the effect of treatment on a patient's well-being, daily activities, and functional status. The Holter/signal averaging electrocardiogram substudy examined the pathophysiology of sudden cardiac death. The neurohormonal substudy determined whether long-term administration of digoxin attenuated the neuroendocrine response in patients with heart failure.