- Class II, III, or IV heart failure as defined by the New York Heart Association (NYHA) functional classification system; abnormal cardiac valve morphology documented by ECHO (subjects with minimal abnormalities [i.e., mild regurgitation/stenosis] can be entered on study - if clarification is needed as to whether an ECHO abnormality is minimal, please contact the GSK medical monitor); or history of known cardiac arrhythmias (except sinus arrythmias) within the past 24 weeks;