ICES study suggests change in guidelines for elective surgery for people with drug-eluting stents

A new study by researchers at the Institute for Clinical Evaluative Sciences (ICES), St. Michael’s Hospital and the Cardiac Care Network of Ontario could have implications for the current guidelines on carrying out elective surgery on patients with coronary stents.

The study, one of the largest evaluations of non-cardiac surgery following stent implantation, found that major non-cardiac surgery is relatively safe once more than 6 months have elapsed after drug-eluting stent implantation, and more than 45 days have elapsed after bare-metal stent implantation.

Surgeons usually wait 12 months to do elective surgery on patients with drug-eluting stents and one month for those with bare-metal stents, because of concerns that the stress of the operation may trigger a heart attack, but waiting too long is also a problem due to disease progression.

“Traditionally we wait 12 months to do elective surgery on patients with drug-eluting stents and one month for those with bare-metal stents – but these are based on recommendations with little scientific backing,” said Dr. Dennis Ko, ICES senior scientist, senior study author and interventional cardiologist at Sunnybrook hospital.

Ko said the findings break conventional wisdom and have important implications since 70 per cent of North American patients now receive drug-eluting stents. Many such individuals may not be able to defer their planned surgery for a year due to progression of disease or illness. A drug-eluting stent (a scaffold) is a stent placed into diseased arteries that is coated with a drug to prevent the artery from narrowing again. A bare-metal stent is a vascular stent without a coating.

The findings suggest that there may be an optimal time window for performing surgery within the year following bare-metal stent implantation.

“While our results do support the recommendation to delay elective non-cardiac surgery until at least 30 to 45 days have elapsed since bare-metal-stent implantation, they further suggest that excessive delays are not helpful,” said lead author Dr. Duminda Wijeysundera, a scientist at the Li Ka Shing Knowledge Institute of St. Michael’s Hospital and ICES. “Conversely, whereas guidelines recommend that surgery be delayed until one year after drug-eluting-stent implantation, our findings instead suggest that surgery can be performed reasonably safely following a six-month delay,” said Wijeysundera, who is also an anesthesiologist at Toronto General Hospital.

Provided that the appropriate safe time interval has elapsed since stent implantation, the risk of non-cardiac surgery for patients with coronary stents is comparable to the risks of otherwise similar patients without stents. The management of non-cardiac surgery after coronary stent implantation is a frequent and important concern, with 1.2 million procedures performed every year in North America alone. Of patients who receive coronary stents, five per cent subsequently undergo non-cardiac surgery within one year, which is about 60,000 patients annually in North America.

ABOUT THE STUDY:

• The cohort consisted of 8,116 Ontario residents who were aged 40 years or older.
• Patients underwent coronary stent implantation within 10 years before their non-cardiac surgery between April 1, 2003 and March 31, 2009.
• Optimal time for performing surgery appears to be from 46 to 180 days after bare-metal-stent implantation.
• Optimal time for performing surgery appears to be more than 180 days after drug-eluting stent implantation.
• The rate of postoperative mortality was 1.2 per cent at 30 days and 5.2 per cent at one year.

The study used data from the Cardiac Care Network of Ontario.

The study “Risk of elective major non-cardiac surgery after coronary stent insertion: A population-based study” is published in the journal Circulation.

Authors: Duminda N. Wijeysundera, Harindra C. Wijeysundera, Lingsong Yun, Marcin Wąsowicz, W. Scott Beattie, James L. Velianou, Dennis T. Ko.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.

The Cardiac Care Network of Ontario (CCN) is a network of 18 member hospitals providing cardiac services in Ontario. In addition to helping plan, coordinate, implement and evaluate cardiovascular care in Ontario, CCN is responsible for developing, maintaining and reporting on the provincial cardiac wait list registry. In the role of monitoring and enhancing quality of cardiac services in Ontario, CCN develops strategies, based on best practices, to better manage cardiovascular disease across the continuum of care, including strategies to prevent acute hospital readmissions, decrease demand on emergency departments and decrease the need for initial and repeat procedures. The Cardiac Care Network of Ontario is funded by the Ontario Ministry of Health and Long-Term Care.

FOR FURTHER INFORMATION PLEASE CONTACT:

• Communications, ICES
• [email protected]