What have we learned about patients with heart failure and preserved ejection fraction from DIG-PEF, CHARM-preserved, and I-PRESERVE?

Examination of patients with reduced and preserved ejection fraction in the DIG (Digitalis Investigation Group) trials and the CHARM (Candesartan in Heart Failure: Assessment of Reduction in Mortality and Morbidity) trials provides comparisons of outcomes in each of these types of heart failure. Comparison of the patients in these trials, along with the I-PRESERVE (Irbesartan in Heart Failure with Preserved Systolic Function Trial), with patients of similar age, sex distribution, and comorbidity in trials of hypertension, diabetes mellitus, angina pectoris, and atrial fibrillation provides even more interesting insights into the relation between phenotype and rates of death and heart failure hospitalization. The poor clinical outcomes in patients with heart failure and preserved ejection fraction do not seem easily explained on the basis of age, sex, comorbidity, blood pressure, or left ventricular structural remodeling but do seem to be explained by the presence of the syndrome of heart failure.