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Three Part Question

In patients undergoing [coronary artery bypass grafting] is the [radial artery or saphenous vein] the better conduit to achieve [long-term patency]

Clinical Scenario

You are about to perform a coronary artery bypass graft (CABG) on an obese 65-year-old man who has triple-vessel disease involving the left anterior descending (LAD) artery, the first obtuse marginal (OM) branch, and the posterior descending artery (PDA), and an akinetic inferior wall with an estimated ejection fraction of 40%. You wonder whether you should use the saphenous vein (SV) or the radial artery (RA) to graft a heavily diseased PDA or OM to achieve long-term patency.

Search Strategy

Medline 1966–Feb 2005 using OVID interface.
[exp Cardiac Surgical Procedures/OR exp Coronary Artery Bypass/OR exp Myocardial Revascularization/OR exp Cardiovascular Surgical Procedures/OR exp Cardiopulmonary Bypass/OR Coronary art$ bypass.mp OR CABG.mp OR Cardiac surg$.mp] AND (exp radial artery/OR radial arter$.mp] AND [exp veins/OR vein.mp]

Search Outcome

Three hundred and seventy-seven papers were found of which 9 were deemed relevant. Cross-checking of the reference lists revealed another three papers. The 12 papers are presented in the table

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Acar et al, 1992, France	104 consecutive patients underwent CABG with 122 RA grafts The LIMA was used condomitantly as a pedicled graft in 100 cases and the RIMA in 19; a free IMA graft was used in 29 cases and a SV graft in 24	Cohort study (level 3b)	<2 week patency	In the first 50 consecutive patients, RA graft patency was 88%(8/9). 6 patients had localized narrowing of the RA conduit unrelated to the anastomotic lines (spasm)	RA may be a reasonable alternative to other types of conduits to complement the LIMA
Da Costa et al, 1996, Brazil	RA grafts were used in 83 patients (mean age, 54.6 years) undergoing myocardial revascularisation. 61 patients(73%) consented to undergo angiography before hospital discharge	Cohort study (3b)	Immediate patency	59/61 (96.7%) RA grafts were patent and 2 had diffuse spasm. On a second angiogram done in 12 patients after a mean interval of 8.7 months, all grafts were patent. One patient with diffuse early spasms had recurrent symptoms, and a repeated angiogram showed further graft narrowing (string sign). 13/14 (92.8%) SV grafts were patent	With proper care, the RA may be used for CABG with good early results
Chen et al, 1996, USA	60 of 150 patients who underwent CABG with RA grafts had postoperative cardiac catheterization. 94 RA grafts and 26 SV grafts were reviewed	Cohort study (level 3b)	Immediate patency	RA graft was 90/94 (95.7%). 4 grafts showed diffuse narrowing. SV graft patency was 24/26 (92.3%)	The short-term patency rate of RA graft is excellent
Manasse et al, 1996, Italy	The RA was used for myocardial revascularization in 109 patients Group 1 (n=95) The arterial fascia was opened with gentle hydrostatic dilatation, and the graft was anastomosed to the aorta Group 2 (n=14) The graft was branched to another conduit	Cohort study (level 2b)	1 year patency rate	56 patients (52.33%) underwent angiography at a mean interval of 334.42 days: the patency rate of the RA graft was 87.75% in group 1 and 62.5% in group 2. SV graft patency was 35/46 (76.1%) (P=0.67) in group 1. On the contrary, the patency rate of group 2 was comparable with that of SV graft (P=0.36)	The RA is a manageable conduit with very promising early patency, although longer follow-up is mandatory
Possati et al, 1998, Italy	The first 68 consecutive surviving patients in whom a RA graft was proximally anastomosed to the aorta were re-studied after 5 years (59±6.5 months); 48 had previously undergone early angiography	Prospective randomized (2b)	5 year patency	RA graft patency was 57/61 (91.9%). All RA grafts that were patent early after surgery remained patent at the midterm follow-up. Early irregularities in 7 patients disappeared after 5 years. SV graft patency was 43/58 (74.1%)	The midterm angiography results of RA grafts used for myocardial revascularization are excellent, and higher than those for SV grafts. The correct surgical indication is essential
Amano et al, 2001, Japan	475 patients underwent RA grafting. The patients were followed to determine mid-term graft patency, cardiac events and survival	Cohort study (3b)	Within 3-months - patency	SV graft 34/38 (89.5%). RA graft 137/139 (98.6%)	No adverse effects were with the RA grafts at midterm follow-up after CABG, and the patency of the RA graft was similar to that of other arterial grafts
			Beyond 3-months - patency	SV graft 71/79 (89.8%). RA graft 213/229 (93%) patency.
Buxton et al, 2003, Australia	The RA was compared with the free RIMA in CABG in 285 patients <70 years old (group 1) and with the SV in 153 patients >70 years old (group 2). the trial conduit was grafted to the largest available coronary artery other than the LAD. Angiography was scheduled at intervals between 0 and 10 years according to a second random assignment	Prospective, randomized single center (1b)	5-year patency	Estimated graft patency rates were 0.86 in 24 RA grafts (95% CI 0.67-0.99) vs 0.95 in 22 SV grafts (95% CI 0.83-0.99) (P=0.5) in group 2. Cardiac event free survival estimates were 0.84 (95% CI 0.64-0.99) and 0.89% (95% CI 0.762-0.99), respectively (P=0.9)	The 5 year interim results do not support the hypothesis of superior patency or fewer clinical events for RA grafts than for free or SV grafts
Possati et al, 2003, Italy	90 consecutive patients in whom the RA was used as a CABG conduit directly anastomosed to the ascending aorta were assessed angiographically at 105±9 months	Prospective, randomized (1b)	10-year patency	The long term and perfect patency rates were 77/84 (91.6%) and 74/89 (88%) for RA grafts, respectively, versus 80/82 (97.5%) and 79/82 (96.3%) for LIMA grafts. The severity of stenosis of the target vessel clearly influenced long-term RA patency. Comparison with the perfect patency rates for SV grafts (39/73 53.4% yielded a significant difference (p<0.001)	Ten years after surgery, RA grafts have excellent patency and perfect patency rates Appropriate surgical technique and correct indication are the key factors for long-term RA patency
Desai et al, 2004, Canada	In 561 patients at 13 centers, the LIMA was used to bypass the anterior circulation The RA graft was randomly assigned to bypass the major vessel in either the inferior (RCA) or lateral (CX) territory, with the SV graft used for the opposing territory (control)	Prospective, randomized, multicenter (1b)	1 year patency	36/440 (8.2%) RA grafts and 60/440 (13.6%). SV grafts were completely occluded (p=0.009). Diffuse narrowing (string sign) was present in 31/440(7%) RA grafts and 4/440 (0.9%) SV grafts (p=0.001). The abscence of severe native vessel stenosis was associated with an increased risk of occlusion and diffuse narrowing of the RA graft	RA grafts are associated with a lower rate of graft occlusion at one year than SV grafts Becauses the patency of RA grafts depends on the severity of the native vessel stenosis They should be used preferentially for target vessels with high grade lesions
Khot et al, 2004, USA	A total of 35,536 angiographic procedures in 27,211 patients were reviewed; 310 patients had a RA graft. Patients were divided into 3 groups by graft outcome: 1 occluded 2 severe disease (>70% stenosis, or string sign) 3 patent (<70% stenosis)	Cohort study (2b)	Mean follow up after CABG of 565±511 days	The patency rate was 51.3% for RA grafts and 64.0% for SV grafts (p=0.0016). Corresponding rates of severe stenosis were 15.1% and 5.9% (p=0.0003). Women had a worse overall RA patency rate than men (38.9% vs 56.1%, p=0.025)	In patients presenting predominantly with signs and symptoms of myocardial ischaemia after CABG, RA grafts have lower patency rates than SV grafts. Selective use of the RA is warranted, particularly in women
Tatoulis et al, 2004, Australia	Consecutive postoperative angiograms of 2,127 arterial/coronary conduits were evaluated by two observers. Angiograms were performed for cardiac symptoms String signs were considered occlusions. 3,714 SV grafts were evaluated as well	Cohort study (2b)	1 year patency	RA graft patency 96%	Excellent long-term patency of arterial grafts was noted, superior to those of SV grafts Patencies were influenced by conduit, distribution, and presence of coronary artery stenosis
			4 year patency	RA graft patency 89%. Overall SV graft patency 2,266/3,214 (61%)
			5 year patency	SV graft patency 95%
			10 year patency	SV graft patency 71%
			15 year patency	SV graft patency 32%
Zacharias et al, 2004, USA	6 year outcomes were compared in propensity-matched CABG-LIMA-LAD patients with >1 RA graft or vein only grafts (n=925 each). Groups had essentially identical demographic, comorbidity, coronary disease, and operative data	Prospective, randomized (1b)	6 year patency	6 year survival analysis in patients with SV (86.8%) and RA (92.1%) grafts indicated 67% greater overall mortality in the vein-only group. Angiographic data restudied symptomatic patients showed SV graft failure 966/161 (41%) was significantly worse than radial failure 46/157 (29.3%) in patients receiving both types of grafts (p=0.039)	Using RA as a second arterial conduit in CABG-LIMA-LAD as opposed to a vein is associated with better long term graft outcome due to a decrease in late deaths, especially after the third postoperative year

Comment(s)

Several angiographic observational studies have shown that the RA has excellent short-, mid-, and long-term patency when used as a conduit for revascularization (see table) However, Khot et al reported a high rate of both occlusion and severe flow-limiting disease with the use of RA grafts in patients presenting predominantly with recurrent signs or symptoms of myocardial ischemia after CABG. The RA graft results were dramatically inferior to those for internal mammary artery (IMA) bypass grafts and SV grafts. Although angiographic outcomes with the RA graft were poorer in both sexes, women had particularly high rates of occlusion. It should be noted, though, that this study had a number of limitations. The results were confounded by a selection bias, because the sample was limited to patients with symptoms or signs of recurrent ischemia. Thus, the low RA graft patency rate may have been attributable to the high-risk status of the population rather than an intrinsic tendency of the graft itself. Furthermore, previous studies restricted RA graft placement to patients with high-grade stenosis and good distal runoff, whereas in this study, the decision to use a RA graft was made at the discretion of the individual surgeon, thereby mimicking 'real-life' use. As such, the results may have reflected the less stringent criteria for RA bypass. Recently, Zacharias et al evaluated the 6-year outcome of propensity-matched patients undergoing left IMA (LIMA)-to-LAD grafting with one or more additional RA grafts or vein-only grafts (n=925 each). Perioperative outcomes, including death rate, were similar in the two groups, although cumulative survival was better in the patients with the RA graft(s). Angiographic data in restudied symptomatic patients showed a trend for greater RA graft patency. In patients who received both types of grafts, the extent of failure was significantly worse in the vein graft than the RA graft. These findings favor the use of the RA as a second arterial conduit in LIMA-LAD CABG. Possati et al, in a series of 90 consecutive patients with CABG, reported an 88% long-term (mean 105±9 months) angiographic patency of RA grafts anastomosed to an OM or PDA. This rate was lower than for LIMA grafts (96.3%) but significantly higher than for SV grafts (53.4%), supporting the use of the RA as a complementary conduit for myocardial revascularization. Although these results are encouraging, there are few additional long-term randomized, controlled studies on RA graft patency in symptom-free patients. To bridge this gap, the prospective single-center Radial Artery Patency and Clinical Outcome (RAPCO) Study is conducting a 10-year comparison of angiographic patency and cardiac outcome between RA grafts and either free right IMA (RIMA) grafts (n=25, age <70 years) or SV grafts (n=153, age 75 years) branched to the largest available coronary artery other than the LAD. Interim analysis at 5 years showed no differences in angiographic failure rates or major clinical outcomes (namely, survival and cardiac event-free survival) between the groups. However, these findings were based on only a small proportion of the expected angiographic results. Furthermore, the SV graft patency rates were much higher than rates in both previous reports and in the non-study SVs, perhaps because in SV grafts, atherosclerosis and dysfunction begin to increase only 5 to 10 years postoperatively. The final results at 10 years should help to clarify whether RA grafts are superior to RIMA and SV grafts in this setting. The interim results of a second prospective multicenter trial, the Radial Artery Patency Study (RAPS), were published in 2004. The investigators compared the 8- to 12-month protocol-directed angiographic patency of RA and SV grafts to the right or circumflex coronary arteries in 561 patients. Each patient served as his/her own control. Significantly higher patency rates were noted in the RA graft group (91.8% vs. 86.4%; P=0.01; graft occlusion odds ratio=0.53; 95% confidence interval 0.31–0.85); rates of perfect graft patency (i.e., TIMI 3 flow) were similar (87.7% vs. 85.7%, P=0.37). In the RA group, graft patency was similar in the inferior (right coronary) and lateral (circumflex) territories, and perfect patency was highly dependent on the severity of the proximal native coronary artery stenosis (70–89% coronary stenosis: 81.7% patency, 90% stenosis: 91.5% patency). The long-term (5 to 10 years) findings will be assessed in follow-up studies. In summary, RA patency rates exceeded those of SV grafts at all time points, except in one study [Manasse]. The tabulated studies show a 10-year patency of 50–90% for RA grafts and of 30–50% for SV grafts.

Clinical Bottom Line

The RA graft has a significantly better long-term patency than the SV graft. Although these findings are encouraging, the final results of the RAPCO and RAPS trials after 10 years of follow-up in symptom-free patients should help to clarify the long-term patency rates of RA grafts and to determine whether RA grafts yield better results than SV grafts.

References

1. Acar C, Jebara VA, Portoghese M, Beyssen B, Pagny JY, Grare P, Chachques JC, Fabiani J-N, Deloche A, Guermonprez JL, Carpentier AF. Revival of the radial artery for coronary artery bypass grafting. Ann Thorac Surg 1992;54:652–660.
2. Da Costa FDA, da Costa IA, Poffo R, Abuchaim D, Gaspar R, Garcia L, Faraco DL. Myocardial revascularization with the radial artery: a clinical and angiographic study. Ann Thorac Surg 1996;62:475–480.
3. Chen AH, Nakao T, Brodman RF, Greenberg M, Charney R, Menegus M, Johnson M, Grose R, Frame R, Hu E, Choi H-K, Safyer S. Early postoperative angiographic assessment of radial artery grafts used for coronary artery bypass grafting. J Thorac Cardiovasc Surg 1996;111:1208–1212.
4. Manasse E, Sperti G, Suma H, Canosa C, Kol A, Martinelli L, Schiavello R, Crea F, Maseri A, Possati GF. Use of the radial artery for myocardial revascularization. Ann Thorac Surg 1996;62:1076–1082.
5. Possati G, Gaudino M, Alessandrini F, Luciani N, Glieca F, Trani C, Cellini C, Canosa C, Di Sciascio G. Midterm clinical and angiographic results of radial artery grafts used for myocardial revascularization. J Thorac Cardiovasc Surg 1998;116:1015–1021.
6. Amano A, Hirose H, Takahashi A, Nagano N. Coronary artery bypass grafting using the radial artery: midterm results in a Japanese institute. Ann Thorac Surg 2001;72:120–125.
7. Buxton BF, Raman JS, Ruengsakulrach P, Gordon I, Rosacion A, Bellomo R, Horrigan M, Hare DL. Radial artery patency and clinical outcomes: five-year interim results of a randomized trial. J Thorac Cardiovasc Surg 2003;125:1363–1371.
8. Possati G, Gaudino M, Prati F, Alessandrini F, Trani C, Glieca F, Mazzari MA, Luciani N, Schiavoni G. Long-term results of the radial artery used for myocardial revascularization. Circulation 2003;108:1350–1354.
9. Desai ND, Cohen EA, Naylor CD, Fremes SE. A randomized comparison of radial artery and saphenous vein coronary artery bypass grafts. N Engl J Med 2004;351:2302–2309.
10. Khot UN, Friedman DT, Pettersson G, Smedira NG, Li J, Ellis SG. Radial artery bypass grafts have an increased occurrence of angiographically severe stenosis and occlusion compared with left internal mammary arteries and saphenous vein grafts. Circulation 2004;109:2086–2091.
11. Tatoulis J, Buxton BF, Fuller JA. Patencies of 2, 127 arterial to coronary conduits over 15 years. Ann Thorac Surg 2004;77:93–101.
12. Zacharias A, Habib RH, Schwann TA, Riordan CJ, Durham SJ, Shah A. Improved survival with radial artery versus vein conduits in coronary bypass surgery with left internal thoracic artery to left anterior descending artery grafting. Circulation 2004;109:1489–1496.