- Subjects must have failed the initiation, or the up-titration, of a beta-blocker drug due to hemodynamic intolerance within 12 months prior to the Screening Visit. Failure to tolerate beta-blockade for hemodynamic reasons is defined as worsening signs and symptoms of chronic heart failure, hypotension accompanied with symptoms, or evidence of organ hypoperfusion, which in the judgment of the treating physician precluded further treatment with the beta-blocker. This beta-blocker intolerance must have been documented prior to Screening, and a narrative description of the intolerance must be approved by Myogen prior to Randomization.