Carotid artery stenting (CAS) for the treatment of symptomatic carotid stenosis results in a greater number of periprocedural ischemic brain lesions than carotid endarterectomy (CEA), but the individual lesions are smaller in size with CAS, resulting in a similar lesion volume for both procedures. The results, from a substudy of the ICSS trial, were published online December 13, 2012, ahead of print in Stroke.

The International Carotid Stenting Study (ICSS) randomly assigned 1,713 patients with recently symptomatic carotid artery stenosis to CAS (n = 855) or CEA (n = 858). During the 120 days following randomization, there was a significantly greater risk of death, stroke, or MI among those who underwent stenting compared with endarterectomy.

For the ICSS-MRI substudy, Leo H. Bonati, MD, of the University Hospital Basel (Basel, Switzerland), and colleagues employed diffusion-weighted magnetic resonance imaging (DWI) to detect the presence and features of brain lesions following CAS (n = 124) and CEA (n = 107).  

Greater Lesion Number

Far more DWI lesions were seen among CAS patients than CEA patients. Overall, CAS was associated with an 8.8 times higher risk ratio for lesions than CEA (95% CI 4.4-17.5; P < 0.0001; table 1).

Table 1. Prevalence of DWI Lesions

The expected lesion count with CAS compared to CEA was increased among patients with lower than median systolic blood pressure (RR 27.0; 95% CI 9.15-79.7; P = 0.009), history of diabetes (RR 53.7; 95% CI 11.4-253; P = 0.032), hemispheric stroke as the qualifying event (RR 32.8; 95% CI 10.6-101; P = 0.004), and carotid stenosis on the left side (RR 21.0; 95% CI 7.50-58.8; P = 0.032). The number of lesions also was higher for stenting vs. surgery in centers with a policy of using filter cerebral protection devices (RR 19.8; 95% CI 8.40-46.6; P = 0.023).

Lesions of CAS patients were more likely to occur in the cortical areas and subjacent white matter supplied by leptomeningeal arteries (OR 4.2; 95% CI 1.7-10.2; P = 0.002) than those of CEA patients.

On the other hand, individual lesion size was smaller with CAS than CES (P < 0.0001), such that total lesion volume per patient was similar for both groups (P = 0.18).

‘Showers of Emboli’

“Our findings show that stenting may [send] showers of emboli to the brain,” Dr. Bonati said in an e-mail correspondence with TCTMD. “Further research is needed about the exact mechanisms of embolism and how to identify vulnerable patients. Ongoing studies target vascular anatomy, instability of the carotid plaque, and biological markers of atherosclerosis.

“Effort must be taken to reduce the risk of periprocedural embolism,” he continued. “Pending further insight into how to identify patients at risk, patients with unfavorable vascular anatomy or imaging markers of plaque instability, such as increased lipid content, plaque hemorrhage, or necrosis, might be better treated with endarterectomy.”

But Are the Differences Real?

In a telephone interview with TCTMD, Christopher J. White, MD, of the Ochsner Heart and Vascular Institute (New Orleans, LA), drew attention to the lack of difference in volume of plaque in lesions that form after stenting vs. surgery. “[I]t’s not like one is clearly better than the other,” he said.

Moreover, Dr. White asserted that the findings “need to be taken with a huge grain of salt” because of the low level of operator experience in the ICSS-MRI study. According to the paper, operators had performed 8 to 68 CAS procedures prior to entering the substudy.

The higher rate of lesions found in patients who received stents in their left carotid arteries, which are more difficult to access, is just one consequence of low operator experience, he said. “CREST [Carotid Revascularization Endarterectomy Versus Stenting Trial] did not show any of this, and it had more experienced operators.”

Uncertainty Over Filters

An unexpected finding of the study, Dr. Bonati noted, is that outcomes were poorer among patients in whom filter devices were used.

“Filter devices may capture some emboli, but they might also provoke some by dislodging plaque debris or thrombus as the device is passed through the stenosis and placed distally,” he suggested. “Proximal protection devices which arrest or revert blood flow across the lesion during the procedure have shown promising results in pilot studies, again using MRI as the outcome measure. Whether these devices also lead to a reduction in overt periprocedural stroke needs to be investigated in larger-scale clinical trials.”

For his part, Dr. White said the disadvantage seen with filters simply “doesn’t make sense,” given positive evidence from meta-analyses. “I would agree that we don’t have randomized controlled trials demonstrating the superiority of filters,” he acknowledged. “That’s because we don’t think it’s [ethical].” Possible explanations include poor operator experience as well as the fact that use of filters was not randomized, so operators may simply have chosen to use them more often in higher risk patients.

Dr. White added that the advent of proximal protection devices make the finding obsolete anyway, since the devices have essentially replaced filters. “We’ve shown that with [proximal protection], rates of DWIs are far lower than they are with filters. I don’t use filters anymore.”

 

---

Source:
Gensicke H, Zumbrunn T, Jongen LM, et al. Characteristics of ischemic brain lesions after stenting or endarterectomy for symptomatic carotid artery stenosis: Results from the international carotid stenting study–magnetic resonance imaging substudy. Stroke. 2012;Epub ahead of print.

 

 

Related Stories:

• Carotid Stenting Within First Week of Symptoms Carries Higher Risk Than CEA
• Meta-Analysis: Carotid Stenting Tied to Higher Intermediate, Long-Term Risks Than Surgery
• Comparison of Carotid Stenting, Endarterectomy Stirs Up More Debate