After the publication of the Digitalis Investigation Group (DIG) stated that digoxin therapy had no effect on mortality 
but modestly reduced hospitalizations due to worsening heart failure, concerns have been raised regarding the relative efficacy of Serum Digoxin Concentration (SDC). Many previous study described Higher SDCs (greater than 1.0 ng/mL)have been associated with improved left ventricular function but have not shown a beneficial effect on neurohormonal function, hemodynamic profile, or exercise tolerance.
To know association between mortality and hospitalization in patients with heart failure with its variation in SDC, a post hoc analysis of the randomized, double-blinded, placebo-controlled DIG trial, with the main analysis restricted to men with a left ventricular ejection fraction of 45% or less were admitted. The researchers wanted to evaluate the association of SDC, risk of mortality, and risk of hospitalization among patients with heart failure and left ventricular dysfunction.
Harlan M. Krumholz, MD, SM, and colleagues from Department of Internal Medicine, Yale University School of Medicine assigned randomly patients to receive digoxin whom divided into 3 groups based on SDC at 1 month (0.5-0.8 ng/mL; 0.9-1.1 ng/mL, and 
1.2 ng/mL) and compared with patients randomly assigned to receive placebo. For the main outcome was all-cause mortality at a mean follow-up of 37 months.
Then their trial’s result indicate that the effectiveness of digoxin in the DIG trial varied according to patients’ SDCs, such that higher SDCs were associated with higher rates of mortality and hospitalization, and higher SDC’s value (1.2 ng/mL) may be harmful and recommend therapeutic SDCs of approximately 1.0 ng/mL may not provide any clinical benefit compared with placebo.
They stated a conclusion :
Our study is the first, to our knowledge, to examine the association of different SDCs and major clinical end points. Although based on a post hoc analysis of the DIG trial, our results suggest that an SDC of 0.5 to 0.8 ng/mL was associated with lower rates of mortality and hospitalization.
Their finding challenged the belief that digoxin is not associated with mortality among patients with heart failure in sinus rhythm and suggest that the neutral association of digoxin and all-cause mortality reported in the main DIG trial publication likely obscured an association between SDC and mortality.
Sound interesting, isn’t it? Find complete article about The Effect of Digoxin Serum Level on The Survival of Patients with Heart Failure in PDF filetype provided (source: jama.ama-assn.org). Find also Heart Journal you may browse.
