Placebo-controlled, crossover, double-blind study of digitalis in patients with dilated cardiomyopathy in sinus rhythm

Because of the conflicting results from studies examining the usefulness of digitalis in patients with dilated cardiomyopathy (DCM) in sinus rhythm, a prospective, double-blind, crossover, placebo-controlled trial was performed in 13 such patients. After a 28-day washout period, patients received 8 days of betamethyl digoxin and 8 days of matched placebo in random sequence. Clinical response was assessed objectively by exercise performance with the use of respiratory gas-exchange analysis and contractility value determined by echocardiography (Suga index) before and after drug administration. The patients, acting as their own controls, were followed up at 6 months and 1 year. Eight patients responded satisfactorily to digitalis, a response maintained during follow-up; 5 patients had a poor or no response, and the drug was withdrawn. Improvements in oxygen consumption and work capacity in the 8 patients were linked either to an increase in the contractility indices or to an enhanced ventilation:perfusion ratio, as reflected in a reduction of physiologic dead space. The 8 responders had a cardiac volume less than 1050 mL/m(2) and a relatively better prognosis than the 5 nonresponders (cardiac volume >1050 mL/m(2)). Four patients with a Suga index of 1.3 or higher were considered responders to digitalis therapy, whereas 9 patients with an index lower than 1.3 had a controversial and variable response. Indices of cardiac contractility and measurements of cardiac volume can help to determine response to digitalis therapy, but DCM continues to be a diagnostic challenge for clinicians.