Cardiac Surgeons and the Management of Stroke

Atrial fibrillation causes 15% of strokes in the West and the UK.  There is evidence to suggest occlusion of the left atrial appendage percutaneously with a device called the Watchman is as effective as warfarin in decreasing the incidence of stroke.
Does the same apply to exclusion of the appendage by surgical/open means? Surgical exclusion can be done inexpensively using prolene sutures or expensively using devices such as the Atriclip or Tigerpaw. Such exclusion is usually performed concomitantly with other cardiac surgical procedures such as CABG (coronary artery bypass grafting) or mitral valve surgery.  It is a procedure that is essentially risk free and one that may have life changing benefits for the patients. One wonders how often the appendage is closed off in patients with AF undergoing cardiac surgical procedures?
The fact that percutaneous closure of the appendage is effective at decreasing stroke does not necessarily mean that surgical closure will have the same effect - after all surgery itself has procoagulant effects that may have a negative influence. Trial evidence is needed and if surgical closure is effective at decreasing the incidence of stroke, than this procedure, concomitant or even standalone may very well become more common.