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.
Miwa
Senri
S
Division of Cardiovascular Surgery, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada.
Desai
Nimesh
N
Koyama
Tadaaki
T
Chan
Emily
E
Cohen
Eric A
EA
Fremes
Stephen E
SE
D000316:Adrenergic alpha-Agonists / Q000009:adverse effects*; D000925:Anticoagulants / Q000627:therapeutic use; D001241:Aspirin / Q000627:therapeutic use; D001783:Blood Flow Velocity; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D001026:Coronary Artery Bypass / Q000379:methods*; D017558:Elective Surgical Procedures; D005500:Follow-Up Studies; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000517:prevention & control; D006801:Humans; D009543:Nifedipine / Q000627:therapeutic use; D005996:Nitroglycerin / Q000627:therapeutic use; D017534:Radial Artery / Q000000981:diagnostic imaging* / Q000637:transplantation; D011859:Radiography; D012307:Risk Factors; D012501:Saphenous Vein / Q000000981:diagnostic imaging / Q000637:transplantation; D016042:Transplantation, Heterotopic; D014665:Vasodilator Agents / Q000627:therapeutic use
D000316:Adrenergic alpha-Agonists; D000925:Anticoagulants; D002121:Calcium Channel Blockers; D014665:Vasodilator Agents; D005996:Nitroglycerin; D009543:Nifedipine; D001241:Aspirin