Simple Risk Score Predicts Risk After Carotid Stenting

Susan Jeffrey

November 15, 2012

A new study gives guidance on patient features that identify patients at high and low risk for stroke or death after carotid artery stenting (CAS).

Using a population of patients at high surgical risk undergoing stenting, the Stenting and Angioplasty with Protection in Patients at High-Risk for Endarterectomy (SAPPHIRE) worldwide study, researchers identified variables that were independently associated with higher risk, including demographic, clinical history, and lesion anatomy features, with the aim of developing a bedside tool for risk prediction.

"We developed and validated a predictive model and integer-based tool to predict the occurrence of death or stroke within 30 days of CAS," senior author Laura Mauri, MD, from the Cardiovascular Division at Brigham and Women's Hospital, Boston, Massachusetts, concludes.

The tool was validated internally by statistical methods, but the investigators are also in the process of validating it externally in a new dataset, Dr. Mauri told Medscape Medical News. "That being said, it's pretty robust," she said of the tool. "It's been constructed in over 10,000 patients and is already in a form that's easy to use, so we hope it will be able to be used right away by clinicians to estimate risk in individual patients."

Their report was published online November 5 in Stroke, to coincide with its presentation at the American Heart Association Scientific Sessions 2012 in Los Angeles.


Dr. Laura Mauri

The SAPPHIRE trial was a randomized comparison of carotid endarterectomy vs carotid angioplasty and stenting in patients deemed at high surgical risk. However, with only 334 patients, it wasn't large enough to determine the features strongly associated with periprocedural risk, the authors write.

For this analysis, they used data from SAPPHIRE, a single-group prospective study of higher-risk patients undergoing CAS using distal protection. The goal here was to develop and internally validate a model and bedside tool to predict death or stroke within 30 days of stenting in patients at higher surgical risk by using variables that could be collected easily during clinical practice, the authors write. "The prediction model generated here can be used to support decision-making."

Only patients with at least 1 anatomic or comorbid factor associated with elevated surgical risk were included; in all, 10,186 patients were included in the analysis. The overall rate of stroke or death was 3.6% at 30 days after carotid stenting, which, Dr. Mauri said, is "interesting, because the patients who were included in the study were selected for having a high risk for undergoing carotid endarterectomy. And there are certain consensus opinion variables that surgeons feel increase the risk of carotid endarterectomy. Well, those variables are different from the ones that pertain to carotid artery stenting."

They found that elevated age, history of stroke, history of transient ischemic attack, recent myocardial infarction, the need for both cardiac surgery and carotid revascularization, dialysis treatment, the presence of a type II or III aortic arch, a right-sided carotid stenosis, a longer carotid plaque, and a severely tortuous carotid arterial system were all important risk factors for the development of stroke or death within 30 days of carotid stenting.

Table. Independent Predictors of Adverse Outcome at 30 Days After CAS

Predictor P Value
Increased age .006
History of stroke <.001
History of transient ischemic attack presentation .001
Recent (<4 wk) myocardial infarction .006
Dialysis treatment .007
Need for cardiac surgery as well as carotid revascularization .005
Right-sided carotid stenosis .006
Longer carotid plaque .012
Type II or III aortic arch .035
Tortuous carotid arterial system .004


Using these factors, they developed a model and integer-based risk score for predicting stroke or death within 30 days. The model was calibrated and internally validated using bootstrap resampling.

The risk score, included in the paper, assigns points for each risk factors and the sum of the points relates to the level of risk, ranging from a less than 3% risk with 8 points to a greater than 10% risk with 16 or more points.

"If you just look at the table for the risk score, the most powerful predictors obviously are the ones that give you the most points, and patients who needed to have carotid surgery together with coronary revascularization were at very high risk; patients with a recent MI [myocardial infarction], patients undergoing dialysis, those were really strong predictors, in addition to patients with advanced age, particularly those who were over 70 years of age," Dr. Mauri said.

Welcome Addition

Asked for comment on the new findings, Philip B. Gorelick, MD, MPH, medical director of the Hauenstein Neuroscience Center at Saint Mary's Healthcare and professor in the Department of Translational Science and Molecular Medicine at Michigan State University College of Human Medicine in Grand Rapids, said that understanding which patients are at risk after carotid stenting is important because the procedure is being used in those at elevated risk for carotid endarterectomy.

"The study by Wimmer and colleagues was designed to determine predictors of 30-day stroke or death after carotid artery stenting, and has several strengths, including a large sample size (over 10,000 patients) from 364 sites in the US, and an internal validation model," Dr. Gorelick told Medscape Medical News.

"The predictors of adverse events after carotid artery stenting came as no surprise, and beyond age, they predominantly may be classified as significant vascular disease or vascular disease manifestations," he noted.

"The authors also provide an easy to use prediction tool to help classify risk," he added. "Missing from the study is information about the severity of stroke and a measure of quality of life."

Overall, Dr. Gorelick concludes, "the elucidation of these risk predictor factors and the development of a risk prediction tool are welcome additions to practice, and risk predictors and a prediction tool that can be enhanced by further study."

First author Dr. Neil J. Wimmer is supported by the National Institutes of Health. Dr. Mauri receives institutional research support from Boston Scientific, Medtronic, Abbott, Cordis, Sanofi, Bristol-Myers Squibb, Eli Lilly, and Daiichi Sankyo and has consulted for Medtronic.

Stroke. Published online November 5, 2012. Abstract