Level of evidence (Optional)

The classes of recommendation used in this course are listed below.  These classes represent the integration of the weight of scientific evidence with contextual factors such as expert assessment of the magnitude of benefit, usefulness, or efficacy; cost; educational and training challenges; and difficulties in implementation.

For Class I recommendations, high-level prospective studies support the action or therapy, and the risk substantially outweighs the potential for harm.

For Class IIa recommendations, the weight of evidence supports the action or therapy, and the therapy is considered acceptable and useful.

Source:  http://www.heart.org/idc/groups/heart-public/@wcm/@ecc/documents/downloadable/ucm_318152.pdf