Abstract
Objectives
The aim of this study was to compare radiation exposure, assessed by dose-area product (DAP), in right trans-radial approach (RR) versus left trans-radial approach (LR) for coronary procedures.
Background
In LR the catheter course is more similar to trans-femoral approach, thus allowing an easier negotiation of coronary ostia which, in turn, might translate into reduced fluoroscopy time (FT) and radiation exposure as compared to RR.
Methods
We retrospectively selected diagnostic and interventional procedures (PCI) performed by RR or LR at our center from May 2009 to May 2014. We only included in the analysis the procedures in which DAP values were available.
Results
We analyzed 1464 procedures, 1175 of which performed by RR (80.3%) and 289 by LR (19.7%). Median DAP values were significantly higher in RR as compared to LR for diagnostic and interventional procedures (4482 vs. 3540 cGy.cm 2 and 11523 vs. 10086 cGy.cm 2 , respectively; p < 0.05). No significant differences were observed in FT and in contrast volume (CV). In the propensity-matched cohort, consisting of 269 procedures for each group, no significant differences between LR and RR were observed in median DAP values for both diagnostic and interventional procedures (3990 vs. 3542 cGy.cm 2 and 9964 vs. 10216 cGy.cm 2 , respectively; p = ns); FT and CV were also similar. At multiple linear regression analysis laterality of trans-radial approach was not associated with DAP.
Conclusions
In an experienced trans-radial center LR is not associated with a reduction in radiation exposure, FT or CV as compared to RR.
Highlights
- •
Right trans-radial approach is by far more commonly used than left trans-radial approach.
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Left trans-radial approach has the advantage of an easier catheter manipulation, more similar to trans-femoral approach.
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This could reduce fluoroscopy time and radiation exposure.
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We conducted a retrospective study to investigate patient radiation exposure according to the side of trans-radial approach.
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After propensity matching and multivariate analysis, we did not observe differences between left and right trans-radial approach.
1
Introduction
The trans-radial approach is being increasingly adopted in interventional cardiology since it offers many advantages as compared to the traditional trans-femoral approach, mainly represented by a striking reduction in vascular access site complications and bleedings which, in turn, is associated with improved patient outcome, especially in the setting of acute coronary syndromes .
The trans-radial approach was right-sided in the majority of published studies comparing trans-radial approach versus trans-femoral approach ; this reflects the usual setup of most angiographic suites, in which the operator is standing at the right side of the patient. As a consequence, the prevalence of right trans-radial approach (RR) was estimated to be 90% in a recent worldwide survey . Nevertheless, due to anatomic reasons, left trans-radial approach (LR) might allow for an easier manipulation of catheters with a possible reduction of procedural and fluoroscopy time, and, consequently, of radiation exposure.
This issue is clinically relevant, since a widespread adoption of trans-radial approach is still limited by concerns about the steeper learning curve and the risk of increased radiation exposure as compared to trans-femoral approach , although this concern has been recently questioned .
Several studies comparing LR versus RR were performed, but conflicting results were reported, especially as far as patient radiation exposure is considered.
We sought to investigate whether the side of trans-radial approach affects patient radiation exposure in the real world practice of a transradial catheterization laboratory.
2
Material and methods
2.1
Study design
We designed a retrospective, single-center study including diagnostic and interventional coronary procedures performed through trans-radial approach in our laboratory during a 5-years period (from May 2009 to May 2014). We perform more than 1,000 coronary angiography and more than 500 PCI per year; trans-radial approach was introduced in 2003 and represents our routine access being used in > 80% of procedures. Exclusion criteria were the following: 1) unavailability of fluoroscopy time and dose-area product (DAP) values; 2) procedures in patients with previous coronary bypass surgery, which in our laboratory are routinely performed through LR; 3) PCI on chronic total occlusions (CTO). Primary end point of the study was to compare patient radiation exposure between LL and RR for both diagnostic and interventional coronary procedures. Secondary end-points were fluoroscopy time and contrast volume.
2.2
Procedural details
The procedures were performed by 4 expert operators with extensive experience in trans-radial approach; our laboratory is located in a non-teaching hospital, therefore, at the time of the study, we did not have fellows or physicians in training. Both RR and LR were performed with 6 F sheaths; coronary angiography was performed by using standard 6 F Judkins catheters, starting by default with a Judkins right 4.0 for the right coronary artery and a Judkins left 3.5 for the left coronary artery. PCI was performed with standard 6 F guiding catheter, starting by default with extra back-up curves (3.0 to 3.5) for the left coronary artery and with Judkins right 4.0 for the right coronary artery. No dedicated radial catheters were used either for diagnostic procedures or for PCI.
In diagnostic procedures, a bolus of heparin (5,000 UI) was given in order to prevent radial artery occlusion; in PCI, appropriate anticoagulation was achieved either by the administration of heparin, according to activated clotting time, or by the administration or bivalirudin. At the end of the procedure radial hemostasis was systematically obtained by the application of a pneumatic bandage (TR band™, Terumo Corporation, Tokyo, Japan).
All procedural data, including DAP, fluoroscopy time and contrast volume were prospectively recorded on a dedicated database.
2.3
Radiation exposure measurement and angiographic equipment
Patient radiation exposure was measured by the DAP, which is the product of the dose value of the incident radiation by the irradiated field and is measured in cGy.cm 2 . Both DAP and fluoroscopy time, which is measured in minutes (mm:ss), are provided by built-in software of the angiography system, which is periodically calibrated by a technician to ensure reliability.
All the procedures were performed in a single angiographic room equipped with a flat-panel Innova 2000 cardiac angiographic system (General Electric, Fairfield, CT), which allows fluoroscopy and cine acquisition in 4 fields of view: 20, 17, 15 and 12 cm diagonal square. The number of frames is routinely set at 15 s − 1 frame rate for both fluoroscopy and cine acquisition. The interventional cardiologists use lead aprons and thyroid collars, as well as a ceiling-mounted glass shield and a lead skirt along the table to shield scattered radiations. A medical radiation technician operates the X-ray system and is responsible for patient and staff radioprotection.
2.4
Statistical analysis
Clinical and procedural characteristics were compared between procedures performed by LR or RR. Categorical variables are expressed as percentages and were compared by chi-square test or Fisher’s exact test, as appropriate. Continuous variable were checked for normal distribution using histograms and Shapiro–Wilk’s test. The variables are expressed as mean ± SD or median and interquartile range, and were compared by Student’s t-test or Mann–Whitney U-test, as appropriate.
In order to compare radiation exposure between LR and RR adjusting for clinical and procedural confounders, we performed propensity score matching.
A non-parsimonious propensity score for the choice of vascular approach (LR versus RR) was calculated for each patient by logistic regression analysis, entering in the model the following variables: age, gender, body mass index (BMI), clinical indication to the procedure, PCI procedure, kind of PCI (ad hoc, multivessel, primary), placement of intra-aortic balloon pump during the procedure, performing operator, and number of implanted stents.
Ad hoc PCI was defined as every PCI performed immediately after diagnostic coronary angiography; multivessel PCI was defined as a procedure in which PCI on at least 2 different main coronary vessels was performed; primary PCI was defined as a PCI performed during acute ST-elevation myocardial infarction. A nearest neighbor 1:1 matching was then performed; in order to exclude bad matching, we imposed a caliper of 0.2 of the standard deviation of the logit of the propensity score. The overall imbalance Hansen & Bowers chi-square test was used to assess achieved balance; furthermore, in the matched population categorical and continuous variables in radial and femoral groups were compared by chi-square test and t-test to exclude significant differences in covariates.
We also performed multiple linear regression in order to investigate the predictors of radiation exposure. In the regression model, the dependent variable was the natural logarithm of the radiation exposure (LnDAP) because the distribution of the DAP values was positively skewed. Several clinical and procedural characteristics known to be associated with radiation exposure, as well as the side of trans-radial approach and the propensity score, were then forced into the model.
A p value < 0.05 was considered statistically significant. The analyses were performed with SPSS 21.0 for Windows. Propensity score matching was performed with propensity score matching for SPSS, version 3.0 .
2
Material and methods
2.1
Study design
We designed a retrospective, single-center study including diagnostic and interventional coronary procedures performed through trans-radial approach in our laboratory during a 5-years period (from May 2009 to May 2014). We perform more than 1,000 coronary angiography and more than 500 PCI per year; trans-radial approach was introduced in 2003 and represents our routine access being used in > 80% of procedures. Exclusion criteria were the following: 1) unavailability of fluoroscopy time and dose-area product (DAP) values; 2) procedures in patients with previous coronary bypass surgery, which in our laboratory are routinely performed through LR; 3) PCI on chronic total occlusions (CTO). Primary end point of the study was to compare patient radiation exposure between LL and RR for both diagnostic and interventional coronary procedures. Secondary end-points were fluoroscopy time and contrast volume.
2.2
Procedural details
The procedures were performed by 4 expert operators with extensive experience in trans-radial approach; our laboratory is located in a non-teaching hospital, therefore, at the time of the study, we did not have fellows or physicians in training. Both RR and LR were performed with 6 F sheaths; coronary angiography was performed by using standard 6 F Judkins catheters, starting by default with a Judkins right 4.0 for the right coronary artery and a Judkins left 3.5 for the left coronary artery. PCI was performed with standard 6 F guiding catheter, starting by default with extra back-up curves (3.0 to 3.5) for the left coronary artery and with Judkins right 4.0 for the right coronary artery. No dedicated radial catheters were used either for diagnostic procedures or for PCI.
In diagnostic procedures, a bolus of heparin (5,000 UI) was given in order to prevent radial artery occlusion; in PCI, appropriate anticoagulation was achieved either by the administration of heparin, according to activated clotting time, or by the administration or bivalirudin. At the end of the procedure radial hemostasis was systematically obtained by the application of a pneumatic bandage (TR band™, Terumo Corporation, Tokyo, Japan).
All procedural data, including DAP, fluoroscopy time and contrast volume were prospectively recorded on a dedicated database.
2.3
Radiation exposure measurement and angiographic equipment
Patient radiation exposure was measured by the DAP, which is the product of the dose value of the incident radiation by the irradiated field and is measured in cGy.cm 2 . Both DAP and fluoroscopy time, which is measured in minutes (mm:ss), are provided by built-in software of the angiography system, which is periodically calibrated by a technician to ensure reliability.
All the procedures were performed in a single angiographic room equipped with a flat-panel Innova 2000 cardiac angiographic system (General Electric, Fairfield, CT), which allows fluoroscopy and cine acquisition in 4 fields of view: 20, 17, 15 and 12 cm diagonal square. The number of frames is routinely set at 15 s − 1 frame rate for both fluoroscopy and cine acquisition. The interventional cardiologists use lead aprons and thyroid collars, as well as a ceiling-mounted glass shield and a lead skirt along the table to shield scattered radiations. A medical radiation technician operates the X-ray system and is responsible for patient and staff radioprotection.
2.4
Statistical analysis
Clinical and procedural characteristics were compared between procedures performed by LR or RR. Categorical variables are expressed as percentages and were compared by chi-square test or Fisher’s exact test, as appropriate. Continuous variable were checked for normal distribution using histograms and Shapiro–Wilk’s test. The variables are expressed as mean ± SD or median and interquartile range, and were compared by Student’s t-test or Mann–Whitney U-test, as appropriate.
In order to compare radiation exposure between LR and RR adjusting for clinical and procedural confounders, we performed propensity score matching.
A non-parsimonious propensity score for the choice of vascular approach (LR versus RR) was calculated for each patient by logistic regression analysis, entering in the model the following variables: age, gender, body mass index (BMI), clinical indication to the procedure, PCI procedure, kind of PCI (ad hoc, multivessel, primary), placement of intra-aortic balloon pump during the procedure, performing operator, and number of implanted stents.
Ad hoc PCI was defined as every PCI performed immediately after diagnostic coronary angiography; multivessel PCI was defined as a procedure in which PCI on at least 2 different main coronary vessels was performed; primary PCI was defined as a PCI performed during acute ST-elevation myocardial infarction. A nearest neighbor 1:1 matching was then performed; in order to exclude bad matching, we imposed a caliper of 0.2 of the standard deviation of the logit of the propensity score. The overall imbalance Hansen & Bowers chi-square test was used to assess achieved balance; furthermore, in the matched population categorical and continuous variables in radial and femoral groups were compared by chi-square test and t-test to exclude significant differences in covariates.
We also performed multiple linear regression in order to investigate the predictors of radiation exposure. In the regression model, the dependent variable was the natural logarithm of the radiation exposure (LnDAP) because the distribution of the DAP values was positively skewed. Several clinical and procedural characteristics known to be associated with radiation exposure, as well as the side of trans-radial approach and the propensity score, were then forced into the model.
A p value < 0.05 was considered statistically significant. The analyses were performed with SPSS 21.0 for Windows. Propensity score matching was performed with propensity score matching for SPSS, version 3.0 .
3
Results
The study population is represented by 1464 procedures, performed either by RR (n = 1175, 80.3%) or LR (n = 289, 19.7%). Clinical and procedural characteristics are reported in Table 1 . LR patients were older (68.5 ± 12.1 vs. 64.7 ± 11.9 years; p < 0.001) and more often underwent PCI and multivessel PCI as compared to RR patients (53.6% vs. 45.8%; p = 0.017 and 9.7% vs. 5.4%; p = 0.006, respectively). Differently, the rate of primary PCI was higher in RR as compared to LR (14.5% vs. 8.7%; p = 0.009). We also observed significant differences in the rate of LR vs. RR according to the performing operator; the majority of procedures were performed by operator #1 (n = 289) and operator #2 (n = 789) who adopted a different rate of LR (50.9% versus 15.2%).
| LR | RR | p value | |
|---|---|---|---|
| N. of procedures | 289 | 1175 | |
| Age (years) | 68.5 ± 12.1 | 64.7 ± 11.9 | 0.000 |
| BMI (kg/m2) | 27.4 ± 5.3 | 27.5 ± 4.5 | 0.706 |
| BMI ≥ 30 kg/m2 (n, %) | 67 (23.2) | 291 (24.8) | 0.575 |
| Female (n, %) | 90 (31.1) | 322 (27.4) | 0.206 |
| Diabetes (n, %) | 61 (21.1) | 285 (24.3) | 0.279 |
| Hypertension (n, %) | 131 (45.4) | 508 (43.2) | 0.551 |
| Dyslipidemia (n, %) | 112 (38.9) | 483 (41.1) | 0.503 |
| History of smoke (n, %) | 101 (34.9) | 446 (38.0) | 0.377 |
| Acute coronary syndrome (n, %) | 133 (46.0) | 514 (43.7) | 0.485 |
| PCI (n, %) | 155 (53.6) | 538 (45.8) | 0.017 |
| Ad hoc PCI (n, %) | 112 (38.8) | 460 (39.1) | 0.902 |
| Multivessel PCI (n, %) | 28 (9.7) | 63 (5.4) | 0.006 |
| Primary/Rescue PCI (n, %) | 25 (8.7) | 170 (14.5) | 0.009 |
| N stent/PCI | 1.21 | 1.24 | 0.635 |
| IABP (n, %) | 3 (1.0) | 3 (0.3) | 0.062 |
| Operator (n, %) | 0.000 | ||
| #1 | 147 (50.9) | 142 (12.1) | |
| #2 | 120 (41.5) | 669 (56.9) | |
| #3 | 13 (4.5) | 220 (18.7) | |
| #4 | 9 (3.1) | 144 (12.3) |
In patients undergoing only diagnostic angiography, we did not observe statistically significant differences in LR versus RR neither in contrast volume [77 (62–110) ml vs. 80 (64–100) ml; p = 0.971] nor in fluoroscopy time [3:03 (2:00–5:36) vs. 3:12 (2:24–4:36); p = 0.516]; differently, we observed a higher DAP in RR as compared to LR [4482 (2898–6728) cGy.cm2 vs. 3540 (2505–6710) cGy.cm2; p = 0.003]. The same was observed in patients undergoing PCI, with no significant differences between LR and RR in contrast volume [209 (160–265) ml vs. 210 (160–265) ml; p = 0.6] and fluoroscopy time [10:18 (6:42–14:54) vs. 9:42 (7:24–13:00)] but with a significant increase of DAP in RR as compared to LR [11523 (7529–16084) cGy.cm2 vs. 10086 (6937–14300) cGy.cm2; p = 0.03]. After propensity score matching we obtained 2 groups, one for LR and one for RR, each consisting of 269 procedures. The 2 groups were well balanced for clinical and procedural characteristics ( Fig. 1 ); 142 patients (52.8%) underwent PCI in LR group whereas 135 patients (50.2%) underwent PCI in RR group (p = 0.54). No significant differences were observed between LR and RR in DAP [7433 (3398–11513) cGy.cm2 vs. 6525 (3665–10804) cGy.cm2; p = 0.604], fluoroscopy time [6:36 (3:06–11:39) vs. 5:48 (2:48–10:18); p = 0.185] and contrast volume [145 (80–220) ml vs. 120 (74–219) ml; p = 0.232]. Similarly, no significant differences were observed after splitting diagnostic procedures and PCI ( Fig. 2 ). At multiple linear regression analysis incorporating propensity score the following variables were associated to increased radiation exposure (LnDAP): male gender, BMI, PCI, ad hoc PCI, number of stents implanted, acute coronary syndrome at presentation and performing operator. On the contrary, the side of trans-radial approach was not associated to increased radiation exposure ( Table 2 ).
