Radial artery angiographic string sign: clinical consequences and the role of pharmacologic therapy
Senri Miwa1, Nimesh Desai, Tadaaki Koyama
1Division of Cardiovascular Surgery, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada.
Insights
Radial artery grafts can develop a "string sign," a diffuse narrowing, in 7% of patients after coronary artery bypass surgery. Despite this, over half of these grafts maintained adequate blood flow (TIMI 2 or better).
Area of Science:
- Cardiovascular Surgery
- Vascular Grafts
- Interventional Cardiology
Background:
- The radial artery is increasingly utilized as a graft in coronary artery bypass grafting (CABG).
- Postoperative angiography reveals a subset of radial artery grafts exhibit diffuse narrowing, termed "string signs."
Purpose of the Study:
- To investigate the incidence and characteristics of radial artery graft string signs.
- To correlate string sign presence with medication, perioperative factors, and clinical outcomes.
Main Methods:
- Postoperative angiography at 1 year in 440 patients receiving radial artery grafts.
- Visual and quantitative analysis of angiograms to define complete and partial string signs.
- Correlation of angiographic findings with medication compliance and clinical sequelae.
Main Results:
- Radial artery grafts showed a 7.0% incidence of string signs, significantly higher than saphenous vein grafts (0.9%).
- Complete string signs (mean diameter 0.76 mm) were more common than partial signs (0.89 mm).
- Radial artery string signs were associated with perioperative alpha-adrenergic agonist use and target vessel stenosis <90%; 52% had TIMI 2 or better flow.
Conclusions:
- The radial artery string sign occurs in 7% of patients undergoing CABG.
- Despite diffuse narrowing, a significant proportion of radial artery grafts maintain acceptable blood flow.
- String sign presence, particularly with TIMI 1 flow, is linked to adverse postoperative symptoms.
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.
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