[img_inline align=”left” src=”http://padnws01.mcmaster.ca/images/connolly.jpg” caption=”Stuart Connolly/R.Scheffler photo”]May 11- 2000-Canadian cardiologists today reported the results of a major study which found that a more expensive dual-chamber type of cardiac pacemaker had no significant effect on rates of stroke, heart failure or death when compared to a simpler, less complicated and less expensive form of pacemaker.

The Canadian Trial of Physiologic Pacing (CTOPP), published today in the New England Journal of Medicine, shows that, in many patients, simpler pacemakers may be adequate, resulting in health care savings by reducing the hardware costs and the cost of complications.

More than 10,000 pacemakers are implanted annually in Canada and over 40 per cent of these are the dual-chamber type, which cost about $2,500 more than single-chamber pacemakers.

“These results are important because although most physicians took it as a matter of faith that dual-chamber pacing was superior to single chamber pacing, this had never been properly tested,” said Stuart Connolly, professor of medicine at McMaster University and principal investigator of CTOPP.

“These results cast considerable doubt on our preconceived ideas about pacing and show the importance of doing clinical research to evaluate how we practice medicine.”

There was a small reduction in episodes of abnormal heart rhythm with the dual-chamber pacemaker. On the other hand, there were significantly more complications at the time of implantation with it. The study showed that patients with a simple pacemaker, which only paces the lower heart chambers, had virtually the same outcomes over three years as patients with a pacemaker which paces both lower and upper heart chambers.

The only advantage of dual-chamber pacing in this study was a small reduction in heart rhythm abnormality, known as atrial fibrillation, which can cause stroke. Dual-chamber pacing prevented four episodes of atrial fibrillation over three years of follow-up for every 100 patients treated.

Dual-chamber pacemakers have been thought to be an advance over single-chamber devices, and they are used in over 40 per cent of pacemaker patients in Canada, but previously no definitive research study had proven their value.

CTOPP, which was funded by the Medical Research Council of Canada (MRC), is the first large randomized study of its kind worldwide to evaluate the benefits of dual-chamber pacing compared to the simpler single chamber mode of pacing. Although these results show virtually no benefit over three years, they do not exclude a possible benefit emerging over longer follow-up.

There has been a strong trend in clinical practice over the past decade to increasingly use the more expensive dual-chamber devices, but the evidence for doing so is quite weak. These new results show that, on the whole, patients do very well with a simpler, less expensive device.

MRC funded this study by means of a $5 million research grant. More than 200 researchers in over 30 pacemaker centres across Canada performed this study over a period of six years.

“If being able to keep Canadians healthy and to ensure they receive the best treatment they need when their health fails has been a blessing for Canadians, it has been absolutely crucial to our health care system,” said Henry Friesen, president of the MRC. “Health services research and clinical trials such as this one can give us evidence of how effective different treatments are, and of better, more cost-effective ways of delivering services to Canadians. And if we can get that equation right — delivering effective treatments in the most efficient way possible — then we will also be ensuring the maximum value for our health care dollar.”

According to Anne Gillis, a pacemaker specialist, cardiologist and professor at University of Calgary who served on the CTOPP Steering Committee, “The CTOPP Trial is the first large prospective trial to compare the effects of dual-chamber to single-chamber pacemakers on cardiovascular events. This landmark trial indicates that many patients will not benefit substantially from dual-chamber pacing. The CTOPP results are not completely negative as the trial identified some groups of patients who may benefit from dual-chamber pacing.”

“Furthermore, the small benefit of dual-chamber pacing for preventing heart rhythm problems, is an important observation. Indeed, this benefit was observed late following pacemaker implantation suggesting that other potential benefits of dual-chamber pacing may also occur late,” she said. “For this reason, the CTOPP investigators have extended the follow-up of CTOPP patients from three to six years.”

According to Connolly, “this rate of dual-chamber use appears to be high, even though it is much lower than that in the United States where over 70 per cent of pacemakers implanted are dual chamber. The results of this Canadian study should result in a more balanced view of single chamber pacing, which many specialists have, until now, viewed as being markedly inferior to dual-chamber pacing.”