LOS ANGELES –
Mitchel L. Zoler/MDedge News
Dr. Nathan Belkin
The only patients who benefited from postsurgical treatment with dual antiplatelet therapy (DAPT) were those who were symptomatic (had a stroke or transient ischemic attack) prior to their carotid endarterectomy surgery, a minority of the more than 17,000 matched U.S. patients who underwent carotid endarterectomy during 2003-2018 and were part of this analysis, Nathan Belkin, MD, said at the International Stroke Conference, sponsored by the American Heart Association.
Among patients with symptoms prior to their carotid endarterectomy, DAPT at the time of hospital discharge was associated with a 2-year follow-up rate of stroke, transient ischemic attack (TIA), or death of about 8%, compared with a rate of about 11% among similar patients discharged on aspirin only, a statistically significant difference. In contrast, among patients who were asymptomatic prior to their carotid endarterectomy, discharge treatment with aspirin only was associated with a 2-year event rate similar to the rate among patients discharged on DAPT.
Based in part on this finding, Dr. Belkin and associates at the University of Pennsylvania, Philadelphia, now start symptomatic patients scheduled for carotid endarterectomy on DAPT with aspirin plus clopidogrel (Plavix) about 2 weeks before surgery, and then continue the combined regimen long term after surgery. A prospective, randomized study is needed to fully resolve the optimal use of DAPT in patients with significant carotid artery disease scheduled for carotid endarterectomy, but until then, “we’re individualizing DAPT” to patients at high risk because of a prior stroke or TIA who also have no evidence of an elevated bleeding risk, said Dr. Belkin, a vascular surgeon.
“We hypothesize that patients with systemic carotid disease have a systemic disease process and more activated platelets,” which suggests a potential benefit from DAPT, he explained. But the data that Dr. Belkin reported also indicated that recent U.S. use of DAPT in patients undergoing carotid endarterectomy has moved beyond this subgroup. The U.S. national data set that Dr. Belkin used for the analysis, the Vascular Quality Initiative registry maintained by the Society for Vascular Surgery, included 87,074 patients who underwent carotid endarterectomy during 2003-2018. During the entire 16-year period, 30% of patients overall received a prescription for DAPT at hospital discharge, but this level went steadily up during those years. In 2003, the rate of DAPT prescriptions at discharge was below 10% of patients but then rose incrementally over the following years and by 2018 had increased to about 44% despite a prevalence of symptomatic carotid disease closer to about a third of patients.
Dr. Mai N. Nguyen-Huynh
“It’s surprising that so many patients received DAPT for carotid disease” in recent years, commented Mai N. Nguyen-Huynh, MD, a vascular neurologist with Kaiser Permanente Northern California in Oakland. “It’s been thought that DAPT, and especially clopidogrel, was more beneficial for patients with intracranial atherosclerotic disease, but not so much for patients with carotid disease,” she said in an interview. “We don’t always see systemic atherosclerotic disease in patients with carotid artery disease. It’s not standard practice to look for systemic atherosclerotic disease in patients with carotid disease,” unless something in the patient’s presentation suggests wider vascular-disease progression.
The primary analysis that Dr. Belkin and associates ran removed about 16% of the patients who underwent carotid endarterectomy from the database: those who received no antiplatelet drug, those who received only clopidogrel, and those who went home from surgery on an anticoagulant. Among the remaining 72,122 patients, 35% received DAPT at discharge and 65% received aspirin only. The patients averaged 70 years old, 61% were men, 37% had a history of stroke or TIA, and their overall 2-year incidence of stroke, TIA, or death was 7.3%. To adjust for many baseline differences between the patients discharged on DAPT and those who got only aspirin, the researchers used propensity-score sorting to identify 17,398 matched patients from the two treatment subgroups, 24% of the total population. Comparison of these DAPT and aspirin-only subgroups showed no difference in the overall, 2-year rate of stroke, TIA, or death.
However, when the analysis divided the patients into asymptomatic and symptomatic subgroups, those discharged on DAPT showed a statistically significant lower rate of stroke, TIA, or death during 2 years of follow-up. The same symptomatic subgroup also showed a statistically significant lower rate of total mortality during 5 years of follow-up when treated with DAPT compared with aspirin only, again an absolute, between-group difference of about 3 percentage points that was statistically significant, a difference not seen in the asymptomatic patients. The type of treatment that symptomatic patients received had no relationship to their 2-year incidence of stroke or TIA.
To confirm these findings, Dr. Belkin and coworkers ran a multivariate logistic regression analysis on the data collected from all 72,122 patients who underwent carotid endarterectomy and subsequently received either DAPT or aspirin only. The only statistically significant association between treatment and outcome was among the symptomatic patients who received DAPT, who had a significant reduction in their 5-year mortality, compared with symptomatic patients who received only aspirin at hospital discharge.
Ideally, a comparison of DAPT and aspirin-only treatment should also assess the incidence and severity of bleeding events associated with these treatments, but bleeding data were not available in the database, Dr. Belkin said.
Dr. Belkin and Dr. Nguyen-Huynh had no relevant disclosures.
SOURCE: Belkin N et al. Stroke. 2020 Feb;51(suppl 1): Abstract 67.