Before pacemakers, stents and other medical devices for the heart are approved for use by the U.S. Food and Drug Administration, the devises must be put through pre-market testing. A study by the Archives of Internal Medicine reveals, however, that pre-market tests for cardiovascular devices may not disclose or include all of the data for all testing conducted.
Most pre-market tests involve two sets of patients - training patients and treatment patients. According to a Los Angeles Times article, training patients are used by doctors to learn or practice how to insert or use a particular device. And, treatment patients are a different set of patients that are used for the study, after doctors sufficiently learn on the training patients. Researchers at the University of California, San Francisco, state in the LA Times article that most often the statistics from the training patients are not included in the final pre-market study numbers.
This means that the pre-market test numbers not include the statistics from the "practice" time it took the doctors to become proficient with the device. Therefore, the actual risk to patients may not be relayed.
This is significant because, as the LA Times notes, most doctors do not get to practice inserting a device or working with a device before seeing patients. Statistics in the LA Times confirm this, showing that in one study the reported (treatment group) mortality rate was 3.7 percent; however, the mortality rate among the training group was a much higher 9.9 percent.
Since most FDA pre-market tests do not include training group stats, the actual danger that cardiovascular devices and procedures pose to patients is under-reported, not giving patients the true story.