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Late Clinical Outcome/neuro Events In Asymptomatic Versus Symptomatic Isolated Subclavian Steal
Ali F. AbuRahma, MD, Christina Veith, DO, Noah Dargy, MD, Robert Cragon, MD, Suy Sen Hung Fong, MD.
Charleston Area Medical Center Health Education and Research Institute, Charleston, WV, USA.
Objective: Natural history of subclavian steal (SS) is not well defined. This is the largest study to date, to analyze late neuro events of patients with asymptomatic (asx) vs symptomatic (sx) isolated SS in over 5-year period.
Methods: SS detected during routine carotid duplex ultrasound exams (CDUE) done over a 2-year period were analyzed. Late neuro events including TIA/stroke (hemispheric anterior cerebral vs posterior) were recorded for isolated SS (no associated carotid disease). Kaplan Myer analysis for freedom from stroke for isolated sx and asx SS patients and for patients with combined SS and carotid disease was done.
Results: 285 SS were detected during 11,762 CDUE, 191 had retrograde vertebral flow (complete steal) and 94 had bidirectional flow (partial steal), 64% on left and 33% on right. Indications of testing: post CEA/CAS surveillance 27%, surveillance of carotid stenosis 45%, asx carotid screening 8%, hemispheric neuro symptoms 9%, arm claudication/posterior circulation symptoms 12%. 115 (40%) had isolated SS and 60% had associated >70% carotid stenosis. The mean arm pressure differential was 31.8 vs 34.4 mmHg for asx vs sx patients, (p=0.537). Mean systolic pressure for patient with retrograde flow was 105 vs 129 for bidirectional and 126.8 for normal antegrade flow (p > 0.0001). 51 interventions were done for sx patients: 27 PTA/Stent, 5 carotid subclavian bypasses, (for claudication/posterior circulation symptoms), and 19 CEA for associated carotid disease. At a mean follow-up of 34 months (range of 1-79 months) 10 strokes were noted in the whole group, however in 115 patients with isolated SS (85 were initially asx and 30 sx), there was 1 TIA and 2 strokes in asx SS, both were not posterior strokes (1 lacunar hypertensive stroke and 1 cardiac emboli) and no strokes in sx SS.
Kaplan Myer analysis showed at 5 years, freedom from stroke was 97% for the whole series, 97% for patients with isolated SS, 96% for asx SS, 100% for sx SS. (Figure 1)
Conclusions: SS in patients undergoing CDUE is rare, the majority are asx. Isolated SS had relatively benign course with no posterior circulation strokes at 5 years.
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