Radial Artery Angiographic String Sign: Clinical Consequences and the Role of Pharmacologic Therapy

Background The radial artery is an increasingly important graft for coronary artery bypass surgery. Postoperative angiographic studies have shown that a proportion of radial grafts become diffusely narrowed but not occluded, or string signs. Methods Four hundred forty patients receiving a radial artery graft enrolled in a large clinical trial underwent postoperative angiography at 1 year. Angiograms were analyzed visually and quantitatively. A complete string sign was defined as diffuse narrowing along the full length of the graft, while a partial string sign was defined as segmental narrowing. Angiographic findings were correlated with medication compliance and clinical sequelae. Results Thirty-one patients (7.0 %) had radial artery graft string signs versus 4 patients (0.9%) with a saphenous vein graft string sign (p = 0.001). Complete string signs were present in 28 cases, and the mean diameter was 0.76 ± 0.14 mm (mean ± SD), whereas 3 cases had a partial string sign with a diameter of 0.89 ± 0.14 mm. Fifteen radial arteries showed Thrombolysis in Myocardial Infarction Study (TIMI) 1 flow, 3 cases showed TIMI 2 flow, and 13 cases showed TIMI 3 flow. There was no difference in incidence of radial string sign between patients taking nifedipine versus diltiazem postoperatively. Multivariate analysis revealed the presence of radial artery string sign was closely related to the perioperative use of alpha-adrenergic agonists and target vessels stenosis less than 90%. Postoperative symptoms were associated with radial artery string signs with TIMI 1 flow (p = 0.0045). Conclusions In the Radial Artery Patency Study, radial artery string sign was present in 7% of patients. Despite diffuse narrowing, 52% of grafts had TIMI 2 flow or better.