Small-Size vs Large-Size Burr for Rotational Atherectomy

Abstract: Background. Rotational atherectomy (RA) has been traditionally performed via the transfemoral approach, mostly utilizing large guide catheters (≥7 Fr), which can accommodate the passage of large burrs (≥1.75 mm). However, contemporary data show that using smaller sheath and catheter sizes reduces the risk of procedural access-site related complications. Therefore, the aim of this study was to assess the feasibility of performing RA using smaller burrs and subsequently smaller-sized sheath catheters. Methods. A total of 220 patients underwent RA procedures between January 2011 and July 2017. We compared 162 patients who underwent RA using a maximal burr size of 1.5 mm (small-burr group) with 58 patients who underwent RA using burrs >1.5 mm in diameter (large-burr group). Clinical, procedural, safety, and feasibility data were evaluated and compared between the two groups. Results. Baseline characteristics of the two groups were quite similar other than a higher prevalence of smoking (21.0% vs 5.2%; P<.01) and a lower body weight (80.9 ± 17.5 kg vs 86.8 ± 17.2 kg; P=.03) in the small-burr group vs the large-burr group. The indications for the procedure for the small-burr group vs large-burr group were stable angina in 53% vs 62%, unstable angina in 16% vs 17%, non-ST elevation myocardial infarction (MI) in 26% vs 17%, and ST-elevation MI in 3.7% vs 3.4%, respectively (P=NS for all). The target-vessel (TV) diameter was significantly larger in the large-burr group vs the small-burr group (3.5 ± 0.3 mm vs 3.2 ± 0.5 mm, respectively; P<.01). Importantly, a sheath size >6 Fr was used in 56.0% of the small-burr group vs 89.5% of the large-burr group (P<.01). Moreover, in 53% of the small-burr group, a guide catheter >6 Fr was used. Radial access was used in 33% of the small-burr group and 17% of the large-burr group (P=.03). Procedural success was achieved in 93% of the small-burr group and 100% of the large-burr group (P=.07). Conclusion. In the majority of cases, RA can be successfully performed using smaller-sized burrs while achieving a high procedural success rate. Notably, our study also highlights the overuse of large sheaths and catheters to deliver small burrs. These results further support the contemporary strategy of using 6 Fr guide catheters, thereby increasing the possibility of using the radial approach for more complex interventional procedures.

J INVASIVE CARDIOL 2019;31(6):183-186.

Key words: access site, bleeding, femoral, radial, transradial, Rotablator, rotational atherectomy

Over the last years, the use of rotational atherectomy (RA) has regained interest, mostly as an adjunctive therapy for plaque modification and lesion preparation before percutaneous coronary intervention (PCI) with drug-eluting stents.^1-3 Therefore, since plaque debulking is no longer the goal, it stands to reason that smaller burr sizes (burr-to-artery ratio <0.7) can achieve similar procedural and angiographic success rates when compared with more aggressive burr sizing (burr-to-artery ratio >0.7), but with a lower complication rate.^4,5

Smaller burrs can be used through smaller-diameter guiding catheters and arterial sheaths, thus reducing the risk of vascular complications.⁶ Moreover, the use of smaller burrs can facilitate the use of RA via the radial approach, which is known to reduce major bleeding and hospital length of stay when compared with femoral access.^7,8 Therefore, we sought to assess the safety, feasibility, and procedural outcomes of performing RA using small burrs compared with large burrs and subsequently the use of smaller-sized sheaths and catheters.

Methods

Study population and definitions. In this single-center, retrospective analysis, a total of 220 patients underwent RA between January 2011 and July 2017. Data were collected using electronic and paper health records on multiple variables including, but not limited to, demographics and baseline clinical data, access-site route, and procedural characteristics (including sheath, guide catheter, and burr size). The small-burr group comprised patients who underwent RA using a maximal burr size of 1.5 mm, while the large-burr group comprised those who underwent RA using a burr size >1.5 mm. Procedure-related complications occurring in the periprocedural period were recorded. Target-vessel diameter (TVD) was defined according to the larger stent diameter that was used. Periprocedural anticoagulation and antiplatelet strategy, as well as catheters, burr size, and all PCI-related decisions, were undertaken as per the interventional cardiologist’s discretion. Procedural success was defined as the presence of <10% residual stenosis, normal antegrade flow, and absence of coronary dissection.

Statistical analysis. Continuous variables are expressed as mean ± standard deviation, and categorical variables are expressed as number (%). Comparison of continuous variables was performed using the Student’s t-test, and categorical variables were compared using the Chi-square test. All statistical tests were 2-tailed, and differences were considered statistically significant when a P-value was <.05. Data analyses were performed using the Statistical Package for Social Sciences (SPSS) version 24 (IBM).

Results

Data on 220 patients were gathered, including 162 patients who underwent RA with small burrs (≤1.5 mm) and 58 patients with large burrs (>1.5 mm). Baseline characteristics of the two groups were quite similar except for a higher prevalence of smoking (21.0% vs 5.2%; P<.01) and lower body weight (81 ± 18 kg vs 87 ± 17 kg; P=.03) in the small-burr group vs the large-burr group, respectively (Table 1).

The indications for the procedure in the small-burr group vs the large-burr group were: stable angina in 53% vs 62%, respectively; unstable angina in 16% vs 17%, respectively; non-ST elevation myocardial infarction (MI) in 26% vs 17%, respectively; and ST-elevation MI in 3.7% vs 3.4%, respectively (P=NS for all) (Table 1).

When comparing the RA procedural aspects, radial access was overall used in only 29% of the procedures and was most commonly used in the small-burr group (33% vs 17% in the large-burr group; P=.03). The use of larger sheaths and guide catheters was more common in the large-burr group, and a 1.75 mm burr was used in 84% of the cases in this group. The remaining distribution of burr sizes among the two study groups is presented in Figure 1. In the large-burr group, 90% of the patients received a sheath >6 Fr and 81% received a guide catheter >6 Fr, whereas in the small-burr group, 56% of the patients received a sheath >6 Fr and 31% received a guide catheter >6 Fr (Table 2 and Figure 2).

In the majority of cases in both groups, the TVD was between 3-4 mm; however, while this included nearly all patients in the large-burr group, 30% of the patients in the small-burr group had TVD <3 mm (Figure 3). Accordingly, larger-diameter stents were used in the large-burr group (3.5 ± 0.4 mm vs 3.2 ± 0.5 mm in the small-burr group; P<.001). There were no significant differences between the groups in other procedural aspects, such as target vessel, ad hoc interventions, fluoroscopy time, procedure time, and temporary pacemaker insertion. There were no statistically significant differences in terms of procedural success rates between the small-burr group and large-burr group (93% vs 100%, respectively; P=.07).

Discussion

The results of the present work show that larger sheaths and guide catheters were more commonly used in the large-burr group; however, almost two-third of the patients in the small-burr group received a sheath >6 Fr, and moreover, one-third of them received a guide catheter >6 Fr. Radial access was used in one-third of the procedures and was most commonly used in the small-burr group.

The role of RA has shifted from a standalone debulking procedure to a plaque modifying adjunct. As such, RA aims to smooth the lumen and disrupt the continuity of calcium deposits in the vessel, thereby allowing passage of balloons for further lesion preparation for subsequent stenting. This goal is most likely achieved in the majority of cases using a single 1.5 mm burr;^9,10 thus, our results are in line with existing data regarding the safety and efficacy of RA using small burr sizes and a less aggressive debulking strategy.^4,5 Indeed, while previous data show that RA can be performed with a burr-to-artery ratio of <0.7,^4,5 our study shows high success rates with a burr-to-artery ratio of 0.5 (mean burr-to-artery ratio, 0.46 in the small-burr group and 0.54 in the large-burr group).

Importantly, our study highlights the “overuse” of large sheaths and guide catheters to deliver small burrs. In fact, 56% of the patients had a sheath >6 Fr and 31% had a guide catheter >6 Fr when a burr ≤1.5 mm was utilized. In this regard, one may think that certain operators have chosen a larger guide catheter to obtain more support, yet there is still a 25% incongruence between a large sheath inserted (ie, 7 Fr) and a smaller guide catheter used (ie, 6 Fr) (Figure 2). Moreover, a 1.75 mm burr was used in 84% of the cases among the large-burr group, when this burr size can be accommodated in a 6 Fr guide catheter (albeit with some friction).¹⁰ Furthermore, the burr size in the large-burr group was chosen according to the operator preference and not due to failure to cross or complete the procedure with a burr ≤1.5 mm, suggesting therefore that even a higher proportion of the procedures could have been completed using small-sized burrs. As a matter of fact, if a 6 Fr system would have been utilized in all of these patients, only 8 (3.6%) would have truly needed larger guide catheters to accommodate the larger burrs used. Hence, considering that plaque modification can easily be achieved with smaller burrs, a 6 Fr system used for conventional PCI should not represent a problem for RA, and moreover, would have increased the chances of using the radial approach.^11,12

This study emphasizes the fact that small burrs are often sufficient to achieve plaque modification as part of lesion preparation before stenting. Again, even if a 1.75 mm burr is needed, a 6 Fr guide-catheter system should suffice; alternatively, either a 7 Fr Glidesheath Slender introducer (Terumo Medical Corporation) or a sheathless Eaucath guide catheter (Asahi Intecc) can be used to accommodate larger burrs (ie, 2 mm) when needed.

Study limitations. The present study has several limitations. The main limitation lies in the retrospective nature of the study. Additionally, the unbalanced sample size between procedures undertaken using small burr vs large burr limits our results. Another significant limitation of the study is its single-center nature, affecting therefore the external validity of the findings. However, our overall findings are in accordance with the large body of evidence. Last, but not least, TVD was defined based on the implanted stent size rather than quantitative coronary analysis or intravascular imaging.

Conclusion

RA can be successfully performed in the majority of cases with smaller-sized burrs while achieving a high procedural success rate. Notably, our study also highlights the overuse of large sheaths and guide catheters to deliver small burrs. These results further support the contemporary strategy of using 6 Fr guide catheters, thereby increasing the possibilities of using the radial approach for more complex interventional procedures.

References

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8. Valgimigli M, Frigoli E, Leonardi S, et al. Radial versus femoral access and bivalirudin versus unfractionated heparin in invasively managed patients with acute coronary syndrome (MATRIX): final 1-year results of a multicentre, randomised controlled trial. Lancet. 2018;392:835-848.

9. Strisciuglio T, Barbato E. Rotational atherectomy: you will never regret using it but you often regret not having used it! EuroIntervention. 2016;12:1441-1442.

10. Barbato E, Carrie D, Dardas P, et al. European expert consensus on rotational atherectomy. EuroIntervention. 2015;11:30-36.

11. Kotowycz MA, Khan SQ, Freixa X, et al. Rotational atherectomy through the radial artery is associated with similar procedural success when compared with the transfemoral route. Coron Artery Dis. 2015;26:254-258.

12. Kubler P, Zimoch W, Kosowski M, et al. In patients undergoing percutaneous coronary intervention with rotational atherectomy radial access is safer and as efficient as femoral access. J Interv Cardiol. 2018;31:471-477.

From the ¹London Health Sciences Centre, London, Ontario, Canada; ²Hillel-Yaffe Medical Center, Hadera, Israel; ³Ziv Medical Center, Zefat, Israel; and ⁴Keele Cardiovascular Research Group, Centre for Prognosis Research, Institute for Primary Care and Health Sciences, Keele University, Stoke-on-Trent, United Kingdom.

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 January 8, 2019 and accepted January 21, 2019.

Address for correspondence: Rodrigo Bagur, MD, PhD, FAHA, University Hospital, London Health Sciences Centre, 339 Windermere Road, London, ON, Canada N6A 5A5. Email: rodrigobagur@yahoo.com