Inadequate Adherence to Imaging Surveillance and Medical Management in Patients with Duplex Ultrasound-Detected Carotid Artery Stenosis.

BACKGROUND

It is recommended that patients with ≥50% carotid artery stenosis undergo surveillance imaging and atherosclerotic risk reduction medical therapies, regardless of whether revascularization is performed. The objective of this study was to determine rates of adherence to these recommended measures and to identify risk factors for nonadherence.

METHODS

A retrospective analysis was performed of all carotid duplex ultrasound (DUS) from 2016 to 2017 at a single institution. Patients with unilateral or bilateral ≥50% carotid stenosis were included. Primary outcomes were rates and timing of surveillance imaging and medication regimen. Patient and study characteristics were compared using univariate and multivariable analyses. A subgroup analysis of patients with a new finding of carotid stenosis was also performed.

RESULTS

Carotid stenosis >50% was detected in 340 patients. Overall, 182 patients (54%) had follow-up imaging (median 261 days [IQR 166-366]) and 158 patients (46%) had no imaging follow-up (NIFU). NIFU patients had similar rates of aspirin use (86% vs. 88%, P = 0.6) and tobacco cessation counseling (71% vs. 71%, P = 0.8) but had less statin use (85% vs. 94%, P = 0.01) compared to those with imaging follow-up. Subsequent carotid revascularization was more common in patients with imaging follow-up (18% vs. 3%, P < 0.001). NIFU patients were less likely to have Medicare or commercial insurance (54% vs. 75%, P < 0.001). The indication for DUS in NIFU patients, compared to those in follow up, was less commonly neurologic symptoms (11% vs. 14%), more commonly other clinical findings (35% vs. 16%), and more commonly as work up before nonvascular surgery (25% vs. 4%, P < 0.001), respectively. NIFU rates decreased with increasing degree of carotid stenosis. Prior carotid intervention, prior DUS, or DUS ordered by a vascular surgeon were characteristics associated with imaging follow-up (P < 0.05 for all). In a subgroup of 160 patients with new carotid stenosis, a majority (64%) had NIFU and statin use was lower in these patients (82% vs. 96%, P = 0.007). On multivariable analysis, preop indication was predictive of NIFU (odds ratio [OR] 8.1 [95% confidence interval, CI 2.5-26.4], P < 0.001) whereas protective factors included: 70-80% stenosis (OR 0.33 [95% CI 0.14-0.76], P = 0.01), study ordered by vascular surgeon (OR 0.40 [95% CI 0.19-0.83], P = 0.01), and Medicare/commercial insurance (OR 0.36 [95% CI 0.2-0.66], P = 0.001).

CONCLUSIONS

Nearly half of patients found to have ≥50% carotid stenosis on DUS had no imaging follow-up; these patients were less likely to be on recommended statin therapy. The benefits of nonrevascularization-based treatments for carotid disease require adherence to therapy. Forgoing surveillance imaging in patients with hemodynamically significant carotid stenosis should be a shared decision between provider and patient and does not obviate the need for medical therapies.