Multicenter radial artery patency study (RAPS). Study design

Comparing the patency of the left internal mammary in single, sequential, and Y grafts

BACKGROUND

To maximize arterial grafts, left internal mammary (LIMA) sequential and Y grafts are used. The aim is to compare the angiographic patency of the LIMA in these configurations.

METHODS

Between 2002 and 2020, angiography was performed on 1000 patients who either had a single (570), sequential (100), or LIMA y (129) graft. The LIMA was divided into segments (S); S1: LIMA inflow to the first anastomosis, S2: terminal portion of the LIMA to left anterior descending (LAD), and S3; the y-limb anastomosis to a coronary. S1 and S2 patency analysis was carried out with logistic regression.

RESULTS

Failure of the S1 and S2 was 3.7% single, 9% sequential, and 6.2 Y graft (P = .049). Segment 1 failed in 3.7% in single, 5% in sequential, and 0.8% in Y grafts (P = .049). Segment 3 failure was 10.3%. Regression revealed female sex and sequential grafts were associated with decreased S1 and S2 patency.

CONCLUSIONS

Single grafts have the best patency. Failure in sequential grafts leads to increased occlusion of the LIMA inflow, whereas Y-graft failure tends to occlude the y limb. When arterial conduit is sparse, a Y graft should be considered.

The no-touch saphenous vein is an excellent alternative conduit to the radial artery 8 years after coronary artery bypass grafting: A randomized trial

BACKGROUND

In 2004, a prospective randomized trial demonstrated that after 3 years, saphenous veins (SVs) harvested with a no touch (NT) technique had a greater patency than radial grafts for coronary bypass surgery. Here we report the 8-year follow-up data of this trial.

METHODS

The trial included 108 patients undergoing coronary artery bypass grafting (CABG). Each patient was assigned to receive 1 NT SV and 1 radial artery (RA) graft to either the left or right coronary territory to complement the left internal thoracic artery (LITA). Sequential grafting was common, so overall graft patency as well as the patency of each anastomosis were assessed.

RESULTS

Angiography was performed in 84 patients (78%) at mean of 97 months postoperatively. Graft patency were high and similar for both NT and RA: 86% for NT versus 79% for RA (P = .22). The patency of coronary anastomoses was significantly higher with the NT SV grafts (91% vs 81%; P = .046). The NT grafts also had excellent patency in coronary arteries with <90% stenosis (93% patency) and in coronary arteries of small diameter (87% patency) or with mild calcification (88% patency). Patency for the LITA was 92%.

CONCLUSIONS

NT SV grafts have excellent patency similar to that of RA grafts after 8 years. In addition, NT SV grafts can be used in situations that are not ideal for RA grafts.

Lessons learned from Radial Artery Database International ALliance (RADIAL)

Coronary artery bypass graft (CABG) surgery was first performed in the 1960s. As the surgery has evolved, there has been a growing interest in the use of multiple arterial grafts in CABG. Since the re-introduction of the radial artery (RA) to clinical use as a bypass conduit in the 1990s, there have been several randomized controlled trials (RCTs) which have compared saphenous vein graft (SVG) conduits to RA use in CABG. While most trials have shown improved patency of the RA, none of them have been able to demonstrate a survival benefit using the arterial conduit. In this review, we examine the existing RCTs on the subject. We then look at our solution to the decades-old inquiry regarding the RA compared with the SVG. The Radial Artery Database International ALliance (RADIAL) project is an individual patient-level meta-analysis developed to adequately power a study to assess if the RA has superior clinical outcomes compared with the SVG. We describe the process by which this investigation was conducted and the collaboration necessary to achieve success.

Endoscopic Versus “No-Touch” Saphenous Vein Harvesting for Coronary Artery Bypass Grafting

The advantage in terms of wound infection, wound healing, and scarring has resulted in the recent adoption of endoscopic vein harvesting (EVH) as a standard of care for coronary artery bypass grafting in some centers. However, concerns regarding the quality of these grafts have been raised after recent evidence of decreased graft patency, increased reoperation rate, and myocardial infarct, problems that are associated with vascular trauma caused when using this technique. Simultaneously, an atraumatic, “no-touch” technique for harvesting the saphenous vein was developed producing grafts with improved patency comparable to the internal thoracic artery. However, wound complications remain a problem using this technique. This review outlines the need to consider the poor graft quality that may result from EVH and raises the question what is likely to be the “best practice principle” in saphenous vein harvesting?

Radial artery and saphenous vein patency more than 5 years after coronary artery bypass surgery: results from RAPS (Radial Artery Patency Study)

OBJECTIVES

The purpose of this study was to present radial and saphenous vein graft (SVG) occlusion results more than 5 years following coronary artery bypass surgery.

BACKGROUND

In the RAPS (Radial Artery Patency Study) study, complete graft occlusion was less frequent in radial artery compared with SVG 1 year post-operatively while functional occlusion (Thrombolysis In Myocardial Infarction flow grade 0, 1, 2) was similar.

METHODS

A total of 510 patients <80 years of age undergoing primary isolated nonemergent coronary artery bypass grafting with 3-vessel disease were initially enrolled in 9 Canadian centers. Target vessels for the radial artery and study SVG were the right and circumflex coronary arteries, which had >70% proximal stenosis. Within-patient randomization was performed; the radial artery was randomized to either the right or circumflex territory and the study SVG was used for the other territory. The primary endpoint was functional graft occlusion by invasive angiography at least 5 years following surgery. Complete graft occlusion by invasive angiography or computed tomography angiography was a secondary endpoint.

RESULTS

A total of 269 patients underwent late angiography (234 invasive angiography, 35 computed tomography angiography) at a mean of 7.7 ± 1.5 years after surgery. The frequency of functional graft occlusion was lower in radial arteries compared with SVGs (28 of 234 [12.0%] vs. 46 of 234 [19.7%]; p = 0.03 by McNemar's test). The frequency of complete graft occlusion was also significantly lower in radial compared with SVGs (24 of 269 [8.9%] vs. 50 of 269 [18.6%]; p = 0.002).

CONCLUSIONS

Radial arteries are associated with reduced rates of functional and complete graft occlusion compared with SVGs more than 5 years following surgery. (Multicentre Radial Artery Patency Study: 5 Year Results; NCT00187356).

Pulmonary embolism following coronary artery bypass grafting

BACKGROUND

Pulmonary embolism (PE) is a life-threatening complication, with a deceptive clinical presentation following coronary artery bypass grafting (CABG).

METHODS

We identified 13 studies on PE in post-CABG patients, spanning a period of 34 years.

RESULTS

The overall cumulative incidence of PE following CABG was 1.3% (111 PEs in 8553 CABGs).

CONCLUSION

We suggest further prospective randomized studies to examine the effect of saphenous system vein grafting, and choice of low molecular weight heparin prophylaxis on the incidence of post-CABG PE.

Choice of conduit for the right coronary system: 8-year analysis of Radial Artery Patency and Clinical Outcomes trial

BACKGROUND

Previous reports have supported the use of bilateral internal thoracic arteries to revascularize the left coronary circulation. If this becomes standardized practice, the optimal conduit for the right coronary system remains to be established. Our objective is to compare the performance of the radial artery versus the saphenous vein when used to graft the right coronary artery or its branches during an 8-year period after primary coronary artery bypass graft surgery.

METHODS

The Radial Artery Patency and Clinical Outcomes study is a randomized controlled trial comparing radial artery, saphenous vein, and free right internal thoracic artery. Of the 621 patients enrolled in the study, 465 patients received a graft to the right coronary artery or its branches. The retrospectively compiled database was used to establish patency rates and clinical events among these patients.

RESULTS

Absolute graft patency rates were as follows: radial artery, 86.9% of 68 (95% confidence interval, 76.6% to 93.1%); and saphenous vein, 81.2% of 197 (95% confidence interval, 75.1% to 86.1%). Noninferiority tests show that absolute radial patency to saphenous patency is at least 0.9526 (p = 0.025). Kaplan-Meier estimates of angiographic outcomes show no significant difference (log rank p = 0.22). Cardiac events in the right coronary territory occurred in the radial artery group (1.79%) versus the saphenous vein group (4.93%; p = 0.26). Overall mortality was 8.03% in the radial artery group versus 12.5% in the saphenous vein group (p = 0.23).

CONCLUSIONS

The radial artery patency is at least comparable to that of the saphenous vein when grafted to the right coronary artery or its branches. The paucity of clinical events in both grafts is notable. Selection of best conduit may therefore be made according to other factors.

Radial artery conduit for coronary revascularization: as good as an internal thoracic artery?

PURPOSE OF REVIEW

Multiple arterial grafting has been proposed to improve outcomes after coronary bypass surgery. We sought to define the emerging role of the radial artery as an alternative second arterial graft.

RECENT FINDINGS

Despite significant evidence suggesting superiority of bilateral internal thoracic artery grafting, utilization in current clinical practice remains low due to concerns about sternal wound infection and conduit length. Recent clinical trials have started to clarify the role of the radial artery in coronary surgery. This conduit provides superior patency to saphenous vein grafts in the setting of high-grade stenosis regardless of the target territory and with minimal harvest site complications.

SUMMARY

The radial artery is a versatile conduit that provides clinical benefit in a large variety of patients undergoing coronary bypass surgery. Outcomes from ongoing longitudinal clinical trials will further clarify optimal conduit selection strategies.

Contemporary Coronary Graft Patency: 5-Year Observational Data From a Randomized Trial of Conduits

BACKGROUND

The Radial Artery Patency and Clinical Outcomes (RAPCO) study has enrolled patients into two trials to compare the radial artery with the free right internal thoracic artery (if age <70 years) or with saphenous vein (if age >70 years) when grafted onto the largest target other than the left anterior descending artery. Patency outcomes in RAPCO will focus only on the trial graft in each case. However, postoperative angiography from this ongoing study has reassessed all coronary grafts, both trial and nontrial: together these offer a valuable observational overview of likely graft patency in the current era in predominately asymptomatic patients, in contrast to symptom-directed studies that may overestimate the incidence of graft failure.

METHODS

Protocol-directed percutaneous angiography has been performed at intervals weighted toward the end of the study period, or earlier when directed by symptoms. To date, 184 patients have been studied as per protocol, at time points up to 10 years (mean, 3.9), among whom there are 430 nontrial grafts in addition to the 184 trial grafts. Supplementary angiography (percutaneous or computed tomography) was offered at a fixed 5-year time point postoperatively: at this juncture, 193 trial grafts and 469 nontrial grafts have been imaged. Three masked investigators report grafts as angiographically successful if patent from proximal to distal anastomosis inclusive. Failed grafts include greater than 80% stenosis, string sign, or occlusion.

RESULTS

In staggered protocol-directed angiography, overall patency of the in-situ internal thoracic artery grafts and free arterial grafts was 95.5% (210 of 220) and 91.4%% (150 of 164), respectively, which did not differ significantly (p = 0.13). Saphenous vein graft patency was 83.0% (191 of 230) with a trend to higher failure rate compared with free arterial grafts (p = 0.07), and was significantly lower than that of in-situ internal thoracic artery grafts (p = 0.01). At the optional 5-year time point, outcomes are similar to the protocol-directed findings, with patency of in-situ left and right internal thoracic artery grafts of 95.8% (204 of 213), which was significantly greater than that of the other two groups (p = 0.02 and p < 0.001). Patency of free arterial conduits and saphenous vein grafts was 89.1% (139 of 156) and 82.4% (201 of 244), respectively, which did not differ significantly (p = 0.09) at 5 years.

CONCLUSIONS

Although trending to superior patency compared with vein grafts, free arterial conduits have not matched the gold standard achieved by in-situ internal thoracic arteries at trial midpoint. Until the results from RAPCO are available, which will test types of free arterial graft against each other and will compare radial and vein grafts in the longer term, these observational data justify for now our current practice of maximal use of in-situ conduits supplemented by free radial grafts.

Impact of Patient and Target-Vessel Characteristics on Arterial and Venous Bypass Graft Patency

Background— The purpose of this investigation was to determine optimal patient and target-vessel characteristics to maximize arterial and venous graft patency on the basis of data from a large clinical trial.

Methods and Results— Angiographic data on 440 radial artery grafts and 440 saphenous vein grafts were analyzed with methodology to account for within-patient clustering. Multivariable models that incorporated patient demographic, operative, anatomic, and postdischarge medical management were constructed to determine predictors of graft occlusion. Radial artery use was strongly protective against graft occlusion at 1 year after adjustment for all covariates, with a larger protective effect seen in women ( P =0.05 for a subgroup-by-treatment interaction). Among all grafts, diabetes and small target-vessel diameter were associated with an increased risk of graft occlusion, and grafting to a target vessel with more severe proximal stenosis was associated with a decreased risk of graft occlusion. With regard to gender, radial artery graft occlusion at 1 year occurred in similar proportions of men (8.6%) and women (5.3%, P =0.6), whereas, for saphenous vein grafts the comparable occlusion rates were 12.0% and 23.3% respectively ( P =0.02). A history of peripheral vascular disease was associated with an elevated risk of radial artery occlusion but was not associated with early vein graft occlusion ( P =0.02 for a subgroup-by-treatment interaction).

Conclusions— Patients benefit from radial artery–coronary artery bypass conduits as opposed to saphenous vein conduits, and this effect is especially strong in women. Small target-vessel size adversely affected graft patency, and grafting to a target vessel with more severe proximal stenosis improved graft patency.

Patency of the radial artery graft: angiographic study in 209 symptomatic patients operated between 1995 and 2002 and review of the current literature

OBJECTIVES

The purpose of this study is to define the long-term patency of the radial artery (RA) graft and review the current literature.

METHODS

Two hundred and eighty-six RA symptom-directed graft angiograms were studied in 209 patients. The preoperative patient characteristics and intraoperative variables were collected prospectively from patients who had primary coronary artery bypass grafting between 1995 and 2002. A total of 166 (79%) patients were male with a mean age of 65 years. The mean period from operation to re-angiogram was 35 months. Actuarial techniques are not valid in graft patency studies as the time when the graft occluded is not known. Therefore, RA patency was analyzed at four categorical time intervals. The RA was grafted to the left anterior descending artery (LAD) in six patients (2%), diagonal (DIAG) in 29 (10%), obtuse marginal (OM) in 166 (58%), right coronary artery (RCA) in 9 (3%) and posterior descending artery (PDA) in 76 (27%) cases. The graft failure was defined as >or=80% stenosis.

RESULTS

A total of 259 (91%) grafts were patent and 26 (9%) had failed. Most grafts were widely patent or occluded. The LAD/DIAG patency was 30/35 (86%), OM patency 154/166 (93%) and RCA/PDA patency 79/84 (94%). The interval from surgery to angiogram did not affect the RA graft patency (86% at <1 year, 95% at 1-3 years, 89% at 4-5 years, 96% at >5 years).

CONCLUSIONS

Even in a patient cohort with adverse symptoms, excellent RA patency was achieved that remained almost constant through all time intervals studied. Better selection, harvesting and preservation may further improve early patency.

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.

Arterial Conduits Update

Arterial grafting for coronary artery disease has been practiced routinely at the Epworth Hospital for 20 years. Bilateral versus single internal thoracic artery grafts is associated with improved survival, which progressively increased over the 20 years of post-surgery. The average increase in survival was 15% at 20 years. The question of whether to use the radial artery or the saphenous vein graft as supplementary grafts remains unanswered. Current patency data suggest that there is a marginal advantage of radial artery over saphenous graft patency, particularly between 5 and 10 years after surgery. However, there appears to be improved patency of the saphenous vein when used as a coronary artery bypass with the advent of aspirin, lipid-lowering and anti-hypertensive therapy.

A randomized comparison of radial-artery and saphenous-vein coronary bypass grafts

BACKGROUND

In the past decade, the radial artery has frequently been used for coronary bypass surgery despite concern regarding the possibility of graft spasm. Graft patency is a key predictor of long-term survival. We therefore sought to determine the relative patency rate of radial-artery and saphenous-vein grafts in a randomized trial in which we controlled for bias in the selection of patients and vessels.

METHODS

We enrolled 561 patients at 13 centers. The left internal thoracic artery was used to bypass the anterior circulation. The radial-artery graft was randomly assigned to bypass the major vessel in either the inferior (right coronary) territory or the lateral (circumflex) territory, with the saphenous-vein graft used for the opposing territory (control). The primary end point was graft occlusion, determined by angiography 8 to 12 months postoperatively.

RESULTS

Angiography was performed at one year in 440 patients: 8.2 percent of radial-artery grafts and 13.6 percent of saphenous-vein grafts were completely occluded (P=0.009). Diffuse narrowing of the graft (the angiographic "string sign") was present in 7.0 percent of radial-artery grafts and only 0.9 percent of saphenous-vein grafts (P=0.001). The absence of severe native-vessel stenosis was associated with an increased risk of occlusion of the radial-artery graft and diffuse narrowing of the graft. Harvesting of the radial artery was well tolerated.

CONCLUSIONS

Radial-artery grafts are associated with a lower rate of graft occlusion at one year than are saphenous-vein grafts. Because the patency of radial-artery grafts depends on the severity of native-vessel stenosis, such grafts should preferentially be used for target vessels with high-grade lesions.

Radial artery patency and clinical outcomes: five-year interim results of a randomized trial

OBJECTIVE

This study was undertaken to compare elective angiographic patency and cardiac event-free survival of the radial artery graft with that of the free right internal thoracic artery or saphenous vein during a 10-year period after primary coronary artery bypass surgery.

METHODS

This prospective, randomized, single-center trial was conducted on two groups of patients undergoing primary coronary artery bypass surgery. In a younger group (group 1, n = 285, <70 years), the radial artery was compared with the free right internal thoracic artery. In an older group (group 2, n = 153, >/=70 years), the radial artery was compared with the saphenous vein. The trial conduit was grafted to the largest available coronary artery other than the left anterior descending coronary artery. Angiography was scheduled at intervals between 0 and 10 years according to a second random assignment. Patients were followed up at yearly intervals to assess clinical outcomes. Clinical outcomes were analyzed on an intent-to-treat basis during the 10-year follow-up with time-related analyses. This interim study reports angiographic and clinical outcome results during the first 5 years.

RESULTS

Graft patency estimates were as follows: 0.95 (95% confidence interval 0.85-0.99) in 39 radial arteries versus 1.0 in 29 right internal thoracic arteries (P =.4) in group 1, and 0.86 (95% confidence interval 0.67-0.99) in 24 radial arteries versus 0.95 (95% confidence interval 0.83-0.99) in 22 saphenous veins (P =.5) in group 2. Cardiac event-free survival estimates were as follows: 0.91 (95% confidence interval 0.76-0.99) for the radial artery versus 0.82 (95% confidence interval 0.63-0.99) for the right internal thoracic artery (P =.7) in group 1, and 0.84 (95% confidence interval 0.64-0.99) for the radial artery versus 0.89 (95% confidence interval 0.72-0.99) for the saphenous vein (P =.9) in group 2.

CONCLUSION

The 5-year interim results do not support the hypothesis that the radial artery has superior patency to or is associated with fewer clinical events than free right internal thoracic artery or saphenous vein grafts.

Radial artery use is safe in patients with moderate to severe left ventricular dysfunction

BACKGROUND

Using radial artery grafts in patients with moderate to severe left ventricular dysfunction (LVD; ejection fraction < 35%) has been discouraged for the fear that postoperative vasopressor support may cause graft spasm and lead to ischemic complications. We, therefore, examined the safety of radial grafts in aortocoronary bypass (ACB) patients with LVD.

METHODS

Data were collected from 5,455 patients who underwent isolated ACB between January 1995 and September 2001. One thousand eight hundred three patients received a radial artery graft (RadACB), and 3,652 patients did not (NoRadACB). Three hundred seven RadACB, and 819 NoRadACB operations were performed in LVD patients. A matched (age, sex, urgency of operation, diabetes, and renal insufficiency) cohort analysis was performed in LVD patients. Univariate and logistic regression analyses were performed in the entire population and the unmatched RadACB and NoRadACB patient subgroups to examine the effect of radial artery use on postoperative death or myocardial infarction rate.

RESULTS

The matched cohort analysis revealed a similar rate of death or myocardial infarction (RadACB, 11 of 242 patients; NoRadACB, 16 of 242 patients; p = 0.32). Left ventricular dysfunction was associated with a higher rate of death or myocardial infarction in both unmatched groups (RadACB, odds ratio, 2.36; 95% confidence interval, 1.38 to 4.58; p = 0.004; NoRadACB, odds ratio, 1.62; 95% confidence interval, 1.18 to 2.24; p < 0.001) and in the entire population (odds ratio, 1.77; 95% confidence interval, 1.32 to 2.35; p = 0.003). An interaction term for patients with LVD and a radial artery graft, which was forced into the logistic regression model for the entire population, was not predictive of death or myocardial infarction (odds ratio, 1.52; 95% confidence interval, 0.75 to 3.10; p = 0.25).

CONCLUSIONS

Left ventricular dysfunction carries similar risk for postoperative death or myocardial infarction in RadACB and NoRadACB patients. The presence of LVD in isolation is not a contraindication to the use of radial grafting.

The radial artery versus the saphenous vein graft in contemporary CABG: a case-matched study

BACKGROUND

Although use of the internal thoracic artery has been shown to improve outcomes after coronary artery bypass grafting, the same cannot be said of alternative arterial conduits. To determine the benefit of radial artery (RA) grafting, a case-matched review was undertaken.

METHODS

Between March 1994 and March 1999, 2,847 patients underwent isolated coronary artery bypass grafting with a left internal thoracic artery graft, plus saphenous vein grafts (SVGs). Of these patients, 478 also received an RA graft (RA group). The RA patients were matched at a ratio of 1:2 with patients receiving only SVGs and a left internal thoracic artery graft (SVG group; n = 956) using six prognostic risk factors: age, sex, Canadian Cardiovascular Society class, left ventricular grade, number of diseased vessels, and timing of operation. Target vessels were graded according to quality and graftability and were similar between groups. Outcomes were evaluated by univariate and multivariate analyses.

RESULTS

There was a significantly higher prevalence of diabetes, hypertension, and peripheral vascular disease in the RA group (p < 0.05). Although stay in the intensive care unit was shorter in the RA group (RA, 30 +/- 2 hours, and SVG, 37 +/- 2 hours; p = 0.0002), total hospital stay was similar between groups. The incidence of perioperative myocardial infarction was higher in the SVG group (SVG, 31 of 956 or 3.2%, and RA, 6 of 478 or 1.3%; p = 0.02). Multivariate analysis revealed RA grafting to be protective against early mortality and morbidity (odds ratio = 0.58; 95% confidence interval, 0.37 to 0.90; p = 0.015) and late mortality and morbidity including late reintervention (risk ratio = 0.60; 95% confidence interval, 0.37 to 0.93; p = 0.02). Actuarial freedom from events at 36 months postoperatively was greater in the RA group (RA, 95% +/- 2%, and SVG, 86% +/- 4%; p = 0.01).

CONCLUSIONS

Despite a higher prevalence of preoperative comorbidity, patients in the RA group demonstrated improved outcomes after coronary artery bypass grafting. The RA is a viable and beneficial conduit for this operation.