Left Radial Versus Femoral Access for Coronary Angiography in Post-Coronary Artery Bypass Graft Surgery Patients

Abstract: It has been recently demonstrated that coronary angiography of native coronary arteries via the radial artery results in reduced morbidity and mortality, when compared with a femoral approach. However, the efficacy and safety of the transradial approach in patients with coronary grafts is relatively unknown. We performed a retrospective audit of all patients with a history of previous coronary artery bypass graft (CABG) surgery who underwent diagnostic angiography at our institution from 2008-2012. The primary efficacy endpoint was procedure time (minutes), while the secondary efficacy measure was patient radiation exposure (µGy/m²). There were 326 post-CABG patients studied during the defined period, with 254 via femoral approach and 72 via left radial artery. There was no significant difference between the two approaches in procedure time (37 minutes in radial group vs 35 minutes in femoral group; t-test, P=.43). There was also no difference in radiation exposure (7855 µGy/m² in femoral group vs 6825 µGy/m² in radial group; Satterthwaite t-test, P=.08). This study shows the validity of a left radial approach in patients who have undergone angiography post CABG. It suggests that transradial angiography can be safely performed in these patients, without significant increase in procedural time or radiation exposure.

J INVASIVE CARDIOL 2016;28(3):81-84. Epub 2016 February 15.

Key words: access-site complications, transfemoral vs transradial, coronary artery bypass graft surgery

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Coronary angiography via transradial approach (TRA) has gained growing acceptance and operator preference in recent years, based on a reduction in vascular complications and mortality^1,2 when compared with transfemoral approach (TFA). However, it has been suggested that these advantages come at the cost of increased procedure time and fluoroscopy dose.^3-5 Considering the significant morbidity and mortality benefits, increased patient preference and cost effectiveness,^6,7 the European Society of Cardiology now advocates the TRA as the default access route for coronary angiography.⁸ Some parts of the world, including the United States, have been slower to adopt this practice. In 2009, less than 5% of coronary procedures were performed via TRA;⁹ however, this figure has increased substantially in recent years, with estimates that around 20% of procedures are now performed radially.¹⁰ Studies comparing access route preference mainly involve native coronary vessel angiograms, mostly excluding patients post coronary artery bypass graft (CABG) surgery. Although there is insufficient evidence to advocate TRA for patients with coronary grafts, both native arteries and grafts, including the left internal mammary artery, can be commonly studied from the left radial artery. Pedicled left internal mammary graft (LIMA) engagement can be difficult via the right radial artery with conventional catheters; however, this approach is often used by experienced operators with specialized catheters such as Bartorelli or a combination of conventional catheter shapes and wire maneuvers. We sought to compare left TRA with standard TFA for post-CABG patients with respect to procedure time and fluoroscopy dosage. 

Methods

A retrospective analysis was undertaken of demographic and procedural variables of all patients with past CABG surgery who underwent diagnostic coronary angiography without percutaneous intervention (PCI) at our institution between December 2008 and January 2012. All patients had a LIMA graft; patients with pedicled right internal mammary grafts were excluded. Cardiology trainees were equally involved in both TRA and TFA cases during the study and were supervised throughout, with prompt consultant intervention if two failed access attempts or difficulties during the procedure occurred. Choice of TRA or TFA was at the consultant operator’s discretion. 

Procedure details. For TRA catheterization, a satisfactory Allen’s test result was confirmed. After subcutaneous local anesthesia, the radial artery was cannulated with a 5 Fr or 6 Fr Radifocus introducer sheath (Terumo Corporation). Then, 5000 U of intraarterial unfractionated heparin and 2.5 mg of intraarterial verapamil were administered. Radial hemostasis was subsequently obtained using a TR Band (Terumo Corporation), a Velcro-secured wristband with an inflatable compression bladder. Femoral arteries were cannulated similarly with 5 Fr or 6 Fr sheaths and hemostasis was later obtained by digital pressure or FemoStop application. A discretionary 2000 U of unfractionated heparin was given.

The primary efficacy endpoint was minutes of procedure time from local anesthetic infiltration to procedure completion (regardless of need for secondary vascular access). Patient radiation dose (µGy/m²) was a secondary efficacy measure. Access-site complications assessed were radial or femoral dissections (with/without vascular repair) or significant radial/femoral hematoma (>5 cm diameter, bleeding >3 g/L, or requiring blood transfusion). Other complications were cerebrovascular events, coronary dissections and death.

Statistical analysis. Continuous variables are presented as means and categorical variables as counts and percentages. Statistical analysis was done using a combination of t-test (including Satterthwaite for unequal variances), Chi-square test, Fisher’s exact test and multiple regression models. Differences between groups were statistically significant at a P-value <.05. SAS 9.3 statistical software (SAS Institute) was employed for the analysis.

Results

A total of 326 post-CABG patients with at least a LIMA graft were studied during the defined period (254 via TFA and 72 via left TRA). Over ten operators were involved. There were no differences between groups in the baseline demographics of age, body mass index, gender, diabetes, previous cerebrovascular accident, peripheral vascular disease, and aspirin use (Table 1). More acute coronary syndrome indication and clopidogrel use was seen in the TRA group and a borderline excess of renal dysfunction was seen in the TFA cohort.

Neither procedure time nor fluoroscopy dose followed normal distribution, so logarithmic transformation was used in the analysis. There was no significant difference in log procedure time between the two approaches (95% confidence interval [CI] after exponent for femoral group, 34-37; 95% CI for radial group, 33-40; t-test, P=.40). Similarly, there was no significant difference in log fluoroscopy dose between the two approaches (95% CI after exponent for femoral group, 7368-8374; 95% CI for radial group, 5895-7903; Satterthwaite t-test, P=.08) (Figures 1A and 1B). After controlling for confounding factors such as graft numbers and number of vessels studied via multiple regression analysis, no statistical difference between the groups was seen. 

Major complications were limited to 2 cases of acute renal failure and 1 cerebrovascular event in the TFA group, and 1 case of acute renal failure in the TRA group (P=NS). Three failed cases of TRA necessitated crossover to TFA, but there were no crossovers from TFA to TRA. Initially, the majority of procedures were TFA, with a trend toward TRA during the study period (Figure 1C). 

Discussion

This retrospective analysis shows that angiography of post-CABG patients can be safely performed via left TRA without significantly altering procedure time and fluoroscopy dose when compared with TFA. 

The proportion of patients presenting with acute coronary syndrome and previous CABG surgery is around 11% in Australasia¹¹ and 13% internationally.¹² The expectation is that these percentages will continue to increase and that patients with coronary grafts will continue to make up a significant proportion of patients undergoing acute or elective coronary angiography.¹³ While there are numerous studies to support the feasibility and safety of TRA of native coronaries, evidence is limited for performing graft angiography. 

The majority of procedures performed in this analysis were TFA. Despite the preference for and experience in TFA, in addition to the initial TRA learning curve, no significant difference in procedural time and fluoroscopy dose was seen between the two groups, even after controlling for the majority of confounding factors. It is recognized that there will be a period of adjustment when operators change from TFA to TRA and it is estimated that even in experienced operators, it may take up to 25 TRA cases to achieve reasonable proficiency. Due to this learning curve with TRA, there have been concerns that patients and operators may be exposed to longer procedure times and radiation exposure. However, it has been shown that as operators become more experienced in TRA, procedure time and radiation exposure become comparable to TFA procedures.¹⁴ 

Reduced procedure times are important, not just for patient comfort, but also for improving catheter laboratory efficiency and therefore the cost effectiveness of angiography. Previous studies have already shown that TRA is more cost effective than TFA due to earlier ambulation and time to discharge.¹⁵ Our study revealed that the important procedural variable of procedure time, in addition to radiation dose, was unaffected by transradial access route choice for CABG patients, which may result in improved cost efficiency and patient satisfaction, without affecting patient safety. Fluoroscopy dose remains one of the main safety concerns in coronary angiography, due to the link between radiation exposure and malignancy in operators and patients.^16,17 Importantly, we have been able to show that there was no significant difference in radiation dosage between TFA and TRA groups. 

In the only prospective randomized trial comparing TFA and TRA in patients with coronary grafts undergoing diagnostic angiography and/or PCI, Michael et al³ found that TRA resulted in longer procedure times, but no statistically significant increase in patient radiation exposure. Interestingly, in the subgroup of patients who underwent PCI, there was no significant difference between TRA and TFA in regard to procedural time and patient radiation exposure. This was a small trial (128 patients), with only male patients included, thus making it difficult to extrapolate results to female patients. There was also a significant crossover rate from radial to femoral route of 17%, which is more than 4x the rate we experienced (4%). This high crossover rate may have been partly attributable to trainee involvement as first operators and their underlying inexperience in TRA, with this inexperience potentially being a major contributor to the prolonged procedural times in the TRA group. Our results are comparable with two similar sized retrospective studies, where there was no difference found in procedural time and radiation exposure in patients with coronary grafts undergoing PCI¹⁸ and diagnostic angiography.¹⁹ Both of these studies involved over 300 patients and had similar crossover rates from radial to femoral route of around 4%. 

There will continue to be a preference for TFA in the setting of bilateral mammary grafting, as accessing mammary grafts from the contralateral radial artery remains a challenging procedure. This will also be the case in patients with unsatisfactory Allen’s tests or those with contraindications to TRA (current or planned hemodialysis shunts, single remaining radial artery, or local infection).

These data were collected at a time when the cardiology department at our hospital transitioned from a primary femoral to a radial center. Initial operator experience was predominantly in the TFA (Figure 1C), which may have been a factor in the higher crossover rate from TRA to TFA. However, this rate (4%) is similar to previous studies^3,18,19 and is probably attributed to the radial artery being of smaller caliber and having a higher propensity to spasm when compared with the femoral artery. During the study, in keeping with a transition to a radial center, there was a significant trend toward TRA; by 2012, almost one-half of all procedures were performed via the radial artery. 

Study limitations. This was a relatively small, single-center retrospective analysis involving more than ten operators, including trainees, with varying experience and enthusiasm for one angiography route or the other. We were not able to control for operator experience, which potentially could result in a degree of selection bias. Despite these factors, the two groups were well matched and had comparable baseline demographics. All procedures were analyzed and operator radiation dosage and contrast volume were not measured. Major events were recorded, but confounding factors such as heparin and warfarin use were not collected. Postprocedure time to hemostasis and ambulation and/or discharge was not formally assessed, and medium-term complications (femoral pseudoaneurysm formation or radial artery occlusion) were not tracked. There were limited PCIs performed in this patient cohort. Moreover, PCI has a number of potential confounding factors that may affect procedure time and radiation dose depending on the complexity of the case, and are difficult to control for. For these reasons and because we felt “simple angiography” would be more uniform in regard to procedure time and radiation dose, patients who underwent PCI were excluded. 

Conclusion

This study shows the validity of the left TRA in patients who have undergone angiography post CABG. It suggests that transradial angiography can be safely performed in these patients, without significant increase in procedural time or radiation exposure. Larger randomized trials including both diagnostic and percutaneous intervention angiography will need to be conducted to validate this result. 

Acknowledgment. The authors thank Lifeng Zhow, Waitemata District Health Board, Auckland, New Zealand, for statistical analysis. 

References 

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From the Cardiovascular Unit, North Shore Hospital, Auckland, New Zealand.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted June 10, 2015, provisional acceptance given August 10, 2015, final version accepted November 12, 2015.

Address for correspondence: Dr Thomas Pasley, Cardiology Department, North Shore Hospital, Shakespeare Road, Takapuna, Auckland, New Zealand. Email: tfjpasley@hotmail.com