American researchers have pointed out that cardiovascular implants, which are increasingly used across millions of Americans, are not subject to rigorous enough testing, and while this does not that they are "universally unsafe", it might increase the risk, as the US Food and Drug Administration makes sure that all other drugs go through tough testing regimes.

Most of the approvals given to cardiovascular implants, like pacemakers, are based on data from just one trial.

The study, released on Tuesday, has pointed out that over a million American receive implants like pacemakers and stents, but these devices are not put through tough safety tests and the FDA gives its approval based on information from a single study, which "raises questions about the quality of data on which some cardiovascular device approvals are based," said the authors, from UC San Francisco.

Such limited data collected does not seem to have the same kind of high-quality evidence for safety and efficiency as drug which are put through rigorous tests, and this is not what the consumers and doctors expect.

"In general, there is very little data on the strength of evidence for device approval, whereas there is a lot more on pharmaceuticals. We didn't expect that all the devices would need multiple studies or randomized studies. But we were surprised that so many devices were approved on the basis of a single study", said study co-author Dr. Sanket Dhruva.

Details of the study have been published in Wednesday's Journal of the American Medical Assn.