350L1 is a unizonal multiserial multisecular study2 of angh3a" patients. It is a historical-prospective ("retrolective")2 study by design: its 6882 angina patients were assembled from record-review of Mayo Clhxic files, and then followed forward in time. It is unizonal, since all subjects were from a common and geographically discrete source. It is multiserial, or crosssectional, because some o...