Author + information
- Received June 2, 2016
- Revision received October 11, 2016
- Accepted November 3, 2016
- Published online February 6, 2017.
- Yutaka Tanaka, MD, PhD∗ (, )
- Noriaki Moriyama, MD,
- Tomoki Ochiai, MD,
- Takuma Takada, MD,
- Kazuki Tobita, MD,
- Koki Shishido, MD,
- Kazuya Sugitatsu, MD,
- Futoshi Yamanaka, MD,
- Shingo Mizuno, MD,
- Masato Murakami, MD, PhD,
- Junya Matsumi, MD,
- Saeko Takahashi, MD,
- Takeshi Akasaka, MD, PhD and
- Shigeru Saito, MD
- Department of Cardiology and Catheterization Laboratory, Shonan Kamakura General Hospital, Kamakura, Japan
- ↵∗Address for correspondence:
Dr. Yutaka Tanaka, Shonan Kamakura General Hospital, Department of Cardiology and Catheterization Laboratory, 1370-1 Okamoto, Kamakura, Kanagawa 247-8533, Japan.
Objectives The aims of this study were to assess whether the transradial approach can be applied to treat complex chronic total occlusion (CTO) and to determine the predictors of transradial percutaneous coronary intervention (PCI) failure.
Background Consistent data on the outcomes of transradial PCI for treating CTO are scarce.
Methods Consecutive patients who were not receiving hemodialysis and had undergone PCI for CTO were enrolled. The clinical and angiographic characteristics, procedural details, and outcomes of the transradial and transfemoral procedures were examined.
Results In total, 280 and 305 CTO PCI procedures involved transradial and transfemoral access, respectively. The technical success rates did not significantly differ in the entire cohort analysis and the propensity score–matched analysis (74.6% vs. 72.5%; p = 0.51 and 70.6% vs. 73.3%; p = 0.57). When only cases with J-CTO (Multicenter Chronic Total Occlusion Registry of Japan) scores of ≥3 were examined, the transradial group had a significantly lower success rate than the transfemoral group (35.7% vs. 58.2%; p = 0.04). The use of guiding catheter size <7 F (odds ratio [OR]: 5.50; p = 0.008), calcification (OR: 3.20; p = 0.001), occlusion length >20 mm (OR: 2.97; p < 0.001), and age (OR: 1.04; p = 0.03) were associated with transradial CTO PCI failure.
Conclusions Transradial PCI for CTO may be feasible in noncomplex cases, although complex cases still pose a challenge. In cases of transradial PCI for CTO, if possible, guiding catheter size ≥7 F should be selected regardless of lesion morphology. Furthermore, the transfemoral approach should be preferentially considered for complex CTO, particularly in cases with calcification.
Since the first report on transradial percutaneous coronary intervention (PCI) in 1993, its use has become widespread in modern interventional practice because of the associated reduced bleeding risk, early ambulation, and improved patient comfort (1,2). The use of the transradial approach significantly reduces procedure access site–related major bleeding in comparison with the femoral approach (3).
In contrast, transradial PCI has certain disadvantages, such as the learning curve and limitations of guiding catheter size, which may result in inadequate backup support for the guiding catheter (4). Recent enhancements in devices and techniques, along with the accumulation of experience, have improved the procedural outcomes of PCI. However, the application of transradial PCI for complex lesions remains challenging because of these disadvantages.
Some evidence suggests that the transradial approach is clinically equivalent to the femoral approach in the treatment of chronic total occlusion (CTO); however, consistent data on transradial PCI for CTO are scarce (5–7). To investigate whether the transradial technique can be applied to treat complex CTO and to determine the predictors of transradial PCI failure, we examined the clinical and angiographic characteristics, procedural details, and outcomes of transradial and transfemoral PCI for CTO.
During the 10-year period between January 2005 and December 2014, a total of 10,631 PCI procedures were performed at our institution; in particular, 8,379 PCI procedures (78.8%) involved transradial access, 1,573 PCI procedures (14.8%) involved transfemoral access, and 679 PCI procedures (6.4%) involved transbrachial access. After excluding patients receiving hemodialysis, we enrolled a consecutive series of patients who underwent PCI for CTO during this period. This study protocol was approved by the Institutional Review Board. Most of the patients underwent coronary angiography with a 4-F catheter with transbrachial access in advance. CTO was defined as a coronary obstruction with a TIMI (Thrombolysis In Myocardial Infarction) flow grade of 0 and an estimated occlusion duration of ≥3 months. All the included patients had at least 1 occlusion within a native vessel. The occlusion length was measured from the site of total occlusion to that of collateral flow. Angiographic characteristics, such as occlusion length, stump morphology, presence of calcification, presence of tortuosity, and bridging collateral vessels, were recorded. The J-CTO (Multicenter Chronic Total Occlusion Registry of Japan) score, which represents a grading scale for procedural difficulty, was calculated for each lesion on the basis of the lesion characteristics and the prior attempts to open the CTO, as previously described (8). The patients were divided into 2 groups according to the PCI access site: transradial and transfemoral access. In the cases of hybrid access, the access site and guiding size used for the antegrade approach were used.
Procedure and in-hospital outcomes
The patients were pre-treated with aspirin and ticlopidine or clopidogrel and were administered heparin to maintain an activated clotting time of >250 s. All procedures were performed by operators highly experienced in the treatment of CTO, with the access site and interventional strategy left to the discretion of the operator. If the patient had a narrowed radial artery or radial loop, contralateral radial access was considered. Moreover, retrograde angiography from the contralateral side was performed, if necessary. A retrograde approach was considered when angiography showed unfavorable signs for antegrade wiring or when the antegrade approach failed. In our institution, the Extra Back Up guiding catheter (3.5 to 3.75, Medtronic, Minneapolis, Minnesota) was routinely used for the left coronary artery and the Short tip Amplatz Left guiding catheter (1.0 to 1.5, Medtronic) was used for the right coronary artery. A plastic-jacket hydrophilic guidewire was initially used; if required, a guidewire with a tip stiffness of 3 g was used, and the stiffness was directly increased to 12 g. Technical success was defined as the restoration of an antegrade TIMI flow grade of 3 with <50% final residual stenosis. The hospital course was evaluated by individual chart review. Death, Q-wave myocardial infarction, cardiac tamponade, emergent coronary artery bypass grafting (CABG), cerebral infarction, access site–related major bleeding, and contrast-induced nephropathy were recorded as procedural complications. An access site–related major bleeding complication was defined as bleeding requiring blood transfusion and/or surgical repair. Contrast-induced nephropathy was defined as either an increase in serum creatinine level of >25% or an absolute increase in serum creatinine level of 0.5 mg/dl.
We assigned cases to the transradial access and transfemoral access groups according to the PCI access site in order to assess the effect of the access site. Categorical variables are presented as absolute number (percentage), and continuous variables are presented as mean ± SD. The differences between the groups were evaluated by using the chi-square test or Fisher exact test for categorical variables and the 2-tailed Student t test for continuous variables. A p value <0.05 was considered to indicate statistical significance.
Propensity-score matching was used to reduce the effect of selection bias and potential confounding between groups when estimating the effect of the access site on successful recanalization. Possible confounders were chosen for their potential associations with the outcome of interest on the basis of clinical knowledge. The conditional probability of the transradial approach was calculated by fitting a logistic regression model using several variables (age, sex, height, body mass index, current smoking, hypertension, hypercholesterolemia, diabetes mellitus, estimated glomerular filtration rate <60 ml/min/1.73 m2, left ventricular ejection fraction <40%, prior myocardial infarction in other area, previous CABG, peripheral artery disease, anticoagulant therapy, CTO target vessel, 2 CTOs, prior failed CTO, absent stump morphology, calcification, tortuosity, occlusion length >20 mm, presence of bridging collateral vessels, in-stent CTO, and period of PCI). For the propensity score–matched analysis, 1 transradial case was matched with 1 transfemoral case using nearest neighbor matching without replacement. Propensity scores were matched within a caliper width of 0.200; those without a suitable match were excluded from the analysis. Thereafter, the Pearson chi-square test was conducted.
To determine the predictors of procedural failure, logistic regression analysis was performed. The baseline clinical characteristics (age, sex, height, body mass index, current smoking, hypertension, hypercholesterolemia, diabetes mellitus, estimated glomerular filtration rate <60 ml/min/1.73 m2, left ventricular ejection fraction <40%, prior myocardial infarction in other area, previous CABG, peripheral artery disease, anticoagulant therapy, CTO target vessel, and 2 CTOs), angiographic characteristics (prior failed CTO, absent stump morphology, moderate or severe calcification, moderate or severe tortuosity, occlusion length >20 mm, presence of bridging collateral vessels, in-stent CTO, and period of PCI), and procedural characteristics (guiding catheter size <7-F, anchoring technique, and retrograde technique) were included. Significant variables with p values <0.05 in the univariate analysis were entered into the multivariate analysis.
We conducted all analyses using JMP Pro version 11.2.0 (SAS Institute, Cary, North Carolina).
Clinical and angiographic characteristics
From January 2005 to December 2014, 544 patients underwent at least 1 CTO PCI procedure at our hospital. After excluding 36 patients who were receiving hemodialysis, a total of 508 patients with 585 CTO lesions (2 CTOs treated in 33 patients, retried in 39 patients, new CTOs in 5 patients) were included in the present study. Of these procedures, 280 were performed using transradial access (including 6 with hybrid access), and 305 were performed using transfemoral access (including 2 with hybrid access).
The baseline clinical characteristics and lesion characteristics are presented in Table 1. Both groups had an increased prevalence of advanced atherosclerosis and coronary risk factors. There were no significant differences in the prevalence of peripheral artery disease or anticoagulant therapy. The transfemoral group had a higher prevalence of previous CABG compared with the transradial group (7.2% vs. 1.8%; p = 0.002). The target CTO vessels predominantly included the right coronary artery, followed by the left anterior descending coronary artery and left circumflex coronary artery in both groups. The frequency of the RCA as the target vessel was higher in the transfemoral group (52.5%). A total of 90 cases of repeat attempts at CTO PCI were noted, including 43 that were previously performed at our hospital and 47 that were previously performed other hospitals. Moderate or severe calcifications and occlusion length >20 mm were observed significantly more frequently in the transfemoral group (30.2% vs. 17.9%; p = 0.002 and 56.4% vs. 37.1%; p < 0.001). Moreover, the transfemoral group had a significant trend toward higher J-CTO score than the transradial group (p < 0.001).
Procedures and in-hospital outcomes
The procedural characteristics and outcomes are shown in Table 2. Antegrade guiding catheters smaller than 7-F were used in 90.7% of the transradial cases, whereas 7-F or larger guiding catheters were used in 95.4% of the transfemoral cases. The retrograde approach was attempted more frequently in the transfemoral group (33.1% vs. 10.7%; p < 0.001).
Overall technical success was achieved in 74.6% of cases in the transradial group and 72.5% of cases in the transfemoral group (p = 0.51). The transradial procedure appeared to have a lower composite complication rate than the transfemoral procedure, although the difference in the rates was not significant (5.4% vs. 9.2%; p = 0.08). No cases of access site–related bleeding were noted in the transradial group, whereas 9 cases (3.0%) of access site–related bleeding were observed in the transfemoral group, including 3 patients with large hematomas requiring blood transfusion, 3 patients with retroperitoneal bleeding, and 4 patients with pseudoaneurysm requiring surgery. The fluoroscopy time and total amount of contrast media in the transradial cases were significantly lower than those in the transfemoral cases, although there was no significant difference in the occurrence of contrast-induced nephropathy (18.6 min vs. 23.1 min; p < 0.001, 163 ml vs. 205 ml; p < 0.001, and 0% vs. 1.0%; p = 0.25, respectively).
Propensity score–matched cohort analysis
Because the number of noncomplex CTO cases was significantly greater in the transradial group before matching, we performed propensity score matching to reduce the effect of selection bias and potential confounding between the groups. A total of 187 matched pairs of cases in both groups were identified. The baseline clinical and lesion characteristics of the matched groups are shown in Table 3. There were no differences in both the technical success rate and the composite procedural complications (70.6% vs. 73.3%; p = 0.57 and 7.0% vs. 9.1%; p = 0.45, respectively) (Table 4). In contrast, the total amount of contrast media used in the transradial cases was significantly lower than that in the transfemoral cases (165 ml vs. 200 ml; p < 0.001).
Procedure failure in the transradial group
The characteristics of the successful and failed cases in the transradial group are presented in Table 5. Patients in whom PCI for CTO was successful had clinical characteristics that were similar to those in whom the procedure failed, except for age. The failed cases were more likely to have moderate or severe calcification (33.8% vs. 12.5%; p < 0.001), occlusion length >20 mm (54.0% vs. 31.1%; p < 0.001), absent stump (60.6% vs. 44.0%; p = 0.02), and J-CTO score ≥3 (25.4% vs. 4.8%; p < 0.001). Moreover, failed cases had a higher prevalence of the usage of a guiding catheter size of <7-F (97.2% vs. 88.5%; p = 0.03).
Figure 1 shows the prevalence of the successful and failed cases according to the J-CTO score. There were no significant differences in the success rates between the groups with J-CTO scores of 0, 1, and 2; however, in the cohort with J-CTO scores ≥3, the transradial group had a lower prevalence of technical success than the transfemoral group (35.7% vs. 58.2%; p = 0.04).
Predictors of transradial CTO PCI failure
According to the multivariate analysis, transradial procedure failure was associated with the use of guiding catheter size <7-F (odds ratio [OR]: 5.50; 95% confidence interval [CI]: 1.49 to 35.8; p = 0.008), moderate or severe calcification (OR: 3.20; 95% CI: 1.57 to 6.55; p = 0.001), and occlusion length >20 mm (OR: 2.97; 95% CI: 1.62 to 5.52; p < 0.001), and age (OR: 1.04; 95% CI: 1.00 to 1.07; p = 0.03), whereas transfemoral procedure failure was associated with bridging collateral vessels (OR: 4.71; 95% CI: 1.94 to 12.0; p < 0.001), absent stump (OR: 3.35; 95% CI: 1.90 to 6.13; p < 0.001), and occlusion length >20 mm (OR: 2.13; 95% CI: 1.21 to 3.83; p = 0.008) (Table 6). Failure of delivery of devices such as microcatheters, balloons, or stents was more commonly observed with the transradial procedure than with the transfemoral procedure (2.9% vs. 0.7%; p = 0.08) (Table 2). Of the 66 patients with failed transradial CTO PCI procedures, 24 underwent repeat PCI; finally, 17 patients were treated successfully via transfemoral PCI and 1 patient was treated successfully via transradial PCI.
In the present study, we examined the clinical and angiographic characteristics, procedural details, and outcomes of transradial and transfemoral PCI for CTO in order to investigate whether the transradial approach can be applied to treat complex CTO and to determine the predictors of transradial PCI failure. Our results indicate that: 1) transradial CTO PCI may be feasible in cases with J-CTO scores of <3 but may be technically challenging in cases with J-CTO scores of ≥3; 2) in transradial CTO PCI, if possible, a guiding catheter size of ≥7-F should be selected regardless of lesion morphology; and 3) the transfemoral approach should be preferentially considered for complex CTO, particularly in cases with moderate or severe calcification.
Transradial CTO PCI may be feasible in noncomplex CTO cases. Recent studies on transradial CTO PCI have indicated that the transradial approach is feasible and clinically equivalent to the transfemoral approach for the treatment of CTO; procedural success rates ranged from 69% to 93% (5–7). Consistent with previous reports, the success rate of transradial CTO PCI in the present study was acceptably high and similar to the transfemoral approach success rate both in the entire cohort analysis and in the propensity score–matched analysis (74.6% vs. 72.5%; p = 0.51 and 70.6% vs. 73.3%; p = 0.57). However, such findings may be related to the selection of cases with noncomplex CTO for the transradial procedure. Although propensity score matching might have reduced the effect of selection bias and potential confounding, many cases with complex CTO remained unmatched and were excluded. Therefore, we compared the results of transradial and transfemoral CTO PCI according to J-CTO score. The J-CTO score was developed as an objective scoring system for predicting the probability of successful guidewire crossing within 30 min (5). This scoring system can be used as an objective tool for predicting lesion difficulty, although it is not associated with the final success rate. The transradial group had a lower technical success rate compared with the transfemoral group when considering cases with J-CTO scores ≥3; however, no such difference was observed when assessing the groups with J-CTO scores of 0, 1, and 2. These results suggest that the transradial approach may be feasible for the treatment of noncomplex CTO, although complex CTO may still pose a technical challenge. Thus, the J-CTO score can be applied to predict the feasibility of transradial CTO PCI.
We found that the use of guiding catheter size <7-F, moderate or severe calcification, occlusion length >20 mm, and age were independent predictors of transradial CTO PCI failure, whereas bridging collateral vessels, absent stump, and occlusion length >20 mm were independent predictors of transfemoral CTO PCI. This discordance may be due partly to the marked insufficiency in terms of backup support via transradial access, rather than the limitations of the device and technical selection. Innovative devices and techniques for PCI have recently been developed, including wires and microcatheters, as well as the intravascular ultrasound–guided wire technique, anchoring technique, retrograde approach using collateral channels, subintimal tracking, and “mother-child” technique (9). All these advancements can be applied with the transradial procedure as well as the 6-F guiding catheter, except for the intravascular ultrasound–guided wire technique with simultaneous microcatheter use. However, the limitation of guiding catheter sizes remains a critical disadvantage of transradial CTO PCI. If possible, guiding catheter size ≥7-F should be selected, regardless of lesion morphology. Moreover, the transfemoral approach should be preferentially considered for CTO, particularly in cases with moderate or severe calcification.
In patients with acute coronary syndromes (ACS), transradial PCI yields better outcomes by reducing vascular access site–related bleeding (10,11). Because patients undergoing primary PCI have an increased risk for bleeding due to the loading doses of antiplatelet drugs and anticoagulant agents, the transradial approach appears to be attractive for preventing access site–related bleeding in the context of ACS. In the present study, we found that the transradial approach was more favorable than the transfemoral approach in terms of access site–related bleeding in the entire cohort (0% vs. 3.0%; p = 0.004), which suggests that the transradial approach may be more favorable in the treatment of CTO, as in the treatment of ACS. In contrast, there is a major difference in lesion pathology between ACS cases and CTO cases. The pathogenic mechanism of ACS includes flesh thrombosis as a result of plaque rupture or erosion, whereas CTO lesions are more complex and characterized by a heavy atherosclerotic plaque burden with fibrocalcific material. Therefore, successful wire crossing and device delivery require sufficient backup support in highly calcified vessels with CTO. Hence, the advantages of the transradial approach might be offset by the disadvantages regarding backup support in the treatment of complex CTO.
The transradial approach is commonly used for regular PCI; however, the advantages of the transradial procedure may be obtained at the indispensable risk of limited backup support. Hence, we should carefully consider the application of the transradial approach in relation to the lesion difficulty in individual CTO cases. Appropriate selection of the approach site is critically important for achieving better results in PCI for CTO. Our results may help identify suitable candidates for the treatment of CTO via the transradial approach.
First, this study was performed at a single center and had a nonrandomized observational study design with unmeasurable confounders. Second, the small sample size may have limited the power of the statistical analysis in the assessment of the difference in technical success rate. Third, most of the procedures were performed by highly experienced operators, and all the decisions including access site and strategy were left to the operator’s discretion. Fourth, the routes from the access site to the coronary ostium were not investigated. Fifth, mid- and long-term outcomes were not evaluated in the present study.
Transradial PCI for CTO may be feasible in cases with J-CTO scores of <3 but may represent a technical challenge in cases with J-CTO scores of ≥3. In transradial CTO PCI, if possible, a guiding catheter size of ≥7-F should be selected regardless of lesion morphology. Moreover, the transfemoral approach should be preferentially considered for complex CTO, particularly in cases with moderate or severe calcification. Our results may help identify suitable candidates for the treatment of CTO via the transradial approach.
WHAT IS KNOWN? There is some evidence that the transradial approach is clinically equivalent to the femoral approach for the treatment of CTO. However, it is unclear whether the transradial technique can be applied to complex CTO.
WHAT IS NEW? We found that transradial CTO PCI may be feasible in noncomplex CTO cases; however, the treatment of complex CTO cases (J-CTO score ≥3) remains technically challenging. Guiding catheter size, presence of calcification, occlusion length, and age are all important indications for transradial PCI for CTO.
WHAT IS NEXT? A prospective analysis of whether the use of this information can yield better procedural outcomes is required.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- acute coronary syndrome
- coronary artery bypass grafting
- confidence interval
- chronic total occlusion
- odds ratio
- percutaneous coronary intervention
- Received June 2, 2016.
- Revision received October 11, 2016.
- Accepted November 3, 2016.
- American College of Cardiology Foundation
- Hamon M.,
- Pristipino C.,
- Di Mario C.,
- et al.
- Rao S.V.,
- Cohen M.G.,
- Kandzari D.E.,
- Bertrand O.F.,
- Gilchrist I.C.
- Morino Y.,
- Abe M.,
- Morimoto T.,
- et al.
- Romagnoli E.,
- Biondi-Zoccai G.,
- Sciahbasi A.,
- et al.