Horner's syndrome after coronary artery bypass surgery.

We established the frequency of Horner's syndrome (HS) in 248 elective patients after coronary artery bypass surgery. Patients were evaluated neurologically pre- and post-operatively and 6 months after surgery. Nineteen patients (7.7%) developed unilateral HS postoperatively, 12 involving the left eye. The finding persisted in 10 patients (4%) at 6 months. When assessed 2 to 6 days, or 6 months, postoperatively, HS tended to be isolated and not associated with C8/T1 plexopathy. Among nondiabetic subjects, hypertensive patients had a higher frequency of HS than normotensive patients (10.6% versus 2.9%, p = 0.05). Among normotensive subjects, diabetic patients had a higher frequency than nondiabetic patients (15% versus 2.9%, p = 0.08). There was no association between HS, age, sex, internal mammary artery grafting, or length of cardiopulmonary bypass time. In summary, HS is a common and sometimes persistent complication of coronary artery bypass surgery. Hypertensive, and possibly diabetic, patients appear to be at greatest risk for developing HS.