• Mean Change From Baseline in Aortic Pulse Wave Velocity (aPWV) at the 12-Week Endpoint [ Time Frame: Baseline and the 12-Week Endpoint (up to Week 12) ] [ Designated as safety issue: No ]
  The 12-week Endpoint is defined as the last scheduled measurement of PWV during the 12-week double-blind treatment period (from Visits 3-5; Weeks 4, 8, and 12, respectively), and Baseline is defined as the PWV measure from Visit 2 (Randomization). Change from Baseline was calculated as the Endpoint value minus the Baseline Value. PWV is used as a measure of arterial stiffness, which is a measure of the cushioning functioning of major vessels like the aorta. The velocity of the PW along an artery is dependent on the stiffness of that artery.
  
  

• Mean Change From Baseline in Augmentation Index (AIx) at the 12-Week Endpoint [ Time Frame: Baseline and the 12-Week Endpoint (up to Week 12) ] [ Designated as safety issue: No ]
  AIx is a surrogate measure of peripheral (not aortic) arterial resistance and is measured by analysis of the pulse wave at the radial artery. AIx = ([delta P/Pulse Pressure] x 100); delta P is defined by a notch near the peak of the pulse wave. Change from Baseline was calculated as the Endpoint value minus the Baseline Value.
  
  
• Mean Change From Baseline in Forced Expiratory Volume in One Second (FEV1) at the 12-Week Endpoint [ Time Frame: Baseline and the 12-Week Endpoint (up to Week 12) ] [ Designated as safety issue: No ]
  FEV1 is a measure of air flow via spirometry. Change from Baseline was calculated as the Endpoint value minus the Baseline Value.
  
  

This is a multicenter, randomized, double-blind, placebo controlled study to evaluate the effect of Fluticasone Propionate/Salmeterol DISKUS 250/50mcg (FSC) BID on arterial stiffness in COPD subjects. Following a 1 to 14 day run-in period, approximately 250 subjects will be randomly assigned to double-blind treatment for 12 weeks. After the 12 week treatment period, subjects in both treatment arms will receive open label Tiotropium bromide Handihaler18mcg (Tio)QD for 4 weeks in addition to their continued study drug (either FSC250/50 or placebo). The primary measure of efficacy is Pulse Wave Velocity (PWV) at Endpoint. Secondary efficacy measures include Augmentation Index (AIx), Biomarkers of cardiovascular disease, measures of lung function. (e.g. FEV1). Safety will be assessed through the collection of adverse events and COPD exacerbations. Exploratory endpoints include the effect of Tiotropium on PWV and AIx when added to placebo or FSC. Treatment groups will be stratified based on current smoking status. There will be a total of 6 study visits (screening, randomization, and after 4, 8, 12 and 16 weeks of treatment). A follow-up phone contact for collection of adverse event and pregnancy information (if applicable) will be conducted approximately 14 days following the last study visit.