Clamping Intolerance Predicted by Low Clamping Pressure in Carotid Stenting

San Francisco, CA—Clamping intolerance occurred in almost one-third of patients undergoing carotid artery stenting (CAS) with embolic protection devices in an Italian registry study. Lower clamping pressure appears to be the best predictor of clamping intolerance, according to results presented at TCT.

Endovascular clamping of the carotid artery can produce clamping intolerance, manifested as hypoperfusion of the ipsilateral hemisphere. This can produce transient neurological symptoms. Investigators led by Giuseppe Giugliano, MD, of the University of Naples Federico II in Italy, examined results from 605 consecutive patients undergoing CAS with the Mo.MA cerebral protection device (Medtronic) between 2010 and 2012 at a single center to determine predictors of clamping intolerance. The study defined clamping intolerance as any transient neurologic deficit observed during occlusion time, though with a complete recovery within 20 minutes from restoration of antegrade flow.

Of the total cohort, 184 patients developed clamping intolerance during the stenting procedure (30.4%); those who experienced clamping intolerance had lower clamping pressure than patients who did not (see Table).

Table. Clamping Intolerance and Clamping Pressure in Carotid Artery Stenting

Analyses showed that clamping pressure was the most consistent predictor of clamping intolerance, with a c-statistic of 0.85 (95% CI, 0.82-0.88). The investigators also looked for predictive power based on clinical characteristics, the presence of internal carotid artery stenosis greater than 90%, the presence of ipsilateral external carotid artery stenosis, the presence of contralateral internal carotid artery stenosis between 75% and 99%, occlusion and arterial pressure change of more than 55 mm Hg. Clamping pressure at or below 40 mm Hg was the most significant predictor found, with an HR for clamping intolerance of 34.2 (95% CI, 19.7-59.6). The best predictor of such low clamping pressure was the presence of contralateral internal carotid artery occlusion (HR 3.1; 95% CI, 1.5-6.2).

“Those operators who want to perform proximal protected carotid artery stenting in patients with contralateral internal carotid artery occlusion should be aware of an increased risk for clamping intolerance,” Dr. Giugliano told TCT Daily. He added that the rate of clamping intolerance seen in this study was surprisingly high, possibly because the study included all comers and thus had a high percentage of elderly patients and those with the type of occlusion that predisposes toward low clamping pressure.

“There are no conditions in which the use of devices using endovascular clamping is not appropriate, but the operators have to bear in mind that, when there is an increased risk for clamping intolerance, it is important to avoid intraprocedural arterial pressure drop and reduce clamping time to a minimum,” Dr. Giugliano said.

Disclosures:
• Dr. Giugliano reports no relevant conflicts of interest.