Boston Scientific Corp’s new leadless implantable heart defibrillator, hailed by some as a breakthrough, should be used on a limited basis until more data are collected, a prominent cardiologist wrote in an editorial of a top medical journal. Leads, or wires that carry electrical pulses from the defibrillator - which is implanted in the chest - to the heart have always been the weak link in these systems, used to treat irregular heart beats. All of the device makers have had problems at one time or another with leads. Boston Scientific bought the leadless technology, known as a subcutaneous implantable cardioverter-defibrillator, or S-ICD, when it acquired Cameron Health last year. The Cameron device was approved by the U.S. Food and Drug Administration in the fourth quarter. “The S-ICD has not yet been shown to be safe and effective in a diverse patient population,” Robert Hauser wrote in the January issue of the Journal of the American College of Cardiology. Hauser, of the Minneapolis Heart Institute, who has been a vocal critic of medical device companies, also noted that the leadless ICD has not even been shown to be as good as the traditional ICDs that use leads. He said the technology is a promising one that could fill important gaps, especially by bringing it to countries where facilities to implant traditional devices is not available, but more data are needed first.