Burr Entrapment in a Percutaneous Coronary Intervention During Rotational Atherectomy: An Experience With 3195 Cases

Objectives. Burr entrapment is a potentially life-threatening complication of rotational atherectomy (RA). However, owing to its infrequency, there have been no major reports on burr entrapment. This study aimed to evaluate the incidence, treatment, and outcomes of burr entrapment. Methods. This multicenter retrospective study analyzed patients who had undergone percutaneous coronary interventions (PCIs) and were treated by RA between May 2013 and March 2022. Results. Of the 22 640 PCI procedures, RA was performed in 3195 patients (14.1%), among whom burr entrapment occurred in 22 patients (0.69%). The mean patient age was 78 ± 8.7 years; 64% were male, and 32% were on dialysis. The entrapped burr size was 1.7 ± 0.2 mm, and the burr/artery ratio was 0.6 ± 0.1. In 20 patients (91%), the burr was extracted by strong manual pullback. The other patients underwent balloon angioplasty at the site of the entrapped burr, which might have provided space for successful burr withdrawal. Major adverse cardiac events occurred in 23% of patients. Tamponade requiring pericardiocentesis occurred in two patients (9%). No patients required emergency surgery or suffered an in-hospital death. Conclusions. Burr entrapment occurred in 0.69% of patients who had undergone RA. Most burrs were extracted by a strong manual pullback. None required emergency surgery, and there were no in-hospital deaths. The results provide a treatment approach and prognosis for burr stuck in the use of RA.

Rotational atherectomy (RA) is frequently used for lesion modification in percutaneous coronary interventions (PCIs) for moderately to severely calcified lesions. Although the benefits of RA are widely recognized, there are inherent risks, such as burr entrapment, slow flow, distal embolization, and coronary perforation. Although coronary perforation and slow flow are well-known complications of RA, burr entrapment has not been studied extensively.

An entrapped burr can be removed by either manual pullback with a large amount of force or dilation at the site of the entrapped burr with balloon angioplasty. Other options include pulling with a snare or extension catheter after cutting the atherectomy catheter shaft and rotawire.^1,2 However, if these methods fail, the burr must be surgically removed. A previous study reported that surgical removal was required in 7 of 18 patients (39%).³ In contrast, only 42 of 1762 (2.7%) patients with perforation due to RA required emergency surgery^.4 Although burr entrapment is a serious complication of RA, no recent contemporary studies have been conducted. The aim of the present study was to examine the frequency, bailout methods, and clinical outcomes of patients with entrapped burrs during RA.

Patient population. This multicenter, retrospective study analyzed the data of consecutive patients who had undergone PCIs and were treated with RA from May 2013 to March 2022. The patients were treated at the Sapporo Cardiovascular Clinic (Sapporo, Japan) and the Shimane University Faculty of Medicine (Shimane, Japan). The indications for RA were as follows: moderately to severely calcified lesions documented by intravascular ultrasound or optical coherence tomography, device-uncrossable lesions, and lesions unresponsive to balloon inflation. The RA settings, such as the guidewire, burr size, burr manipulation, and rotation speed, were determined based on the attending operator’s judgment. Burr entrapment was defined as the inability to move the burr backward in the coronary artery during or after RA.

This study was conducted in accordance with the principles of the Declaration of Helsinki. The ethics committee of each institution approved the study, and the patients provided informed consent for the PCI procedure. All patients underwent PCIs because they were symptomatic, had ischemia documented by stress myocardial scintigraphy, or had a fractional flow reserve of ≤0.80.⁵ To avoid selection bias, all patients with stuck burrs were enrolled in this study.

Procedural and clinical outcomes. When burr entrapment occurred, manual pullback with strong force was tried while the guide catheter was being intubated. If this failed, balloon angioplasty at the site of the entrapped burr, pulling with a snare or extension catheter after cutting the atherectomy catheter shaft and rotawire, or surgical removal was tried based on the operator’s choice.

In-hospital major adverse cardiac events (MACE) were defined as all-cause death, periprocedural myocardial infarction (MI), target vessel revascularization (TVR) with a PCI or coronary artery bypass graft surgery, or tamponade requiring pericardiocentesis or surgery. MI was defined using the third universal definition of myocardial infarction (type 4a).⁶

Of the 22 640 PCI procedures performed during the study period, RA was performed in 3195 patients (14.1%), among whom rotablator burr entrapment occurred in 22 patients (0.69%). The baseline patient and procedural characteristics are shown in Table 1.

The mean age of the patients was 78.0 ± 8.7 years; 14 were males, and 7 were on dialysis. The entrapped burr size was 1.7 ± 0.2 mm, and the burr/artery ratio was 0.6 ± 0.1. In 12 patients, 2 different burr sizes were used, and in all of them, the second burr was stuck.

In all patients, the entrapped burr was removed without surgery (Table 2). Twenty patients underwent extraction by simply pulling harder while deeply intubating the guide catheter. One of the other 2 patients underwent balloon dilation next to the burr with a double guide. For the other patient, an 8-Fr guide was used; balloon angioplasty was performed at the site of the burr, and the burr was extracted.

The in-hospital outcomes are presented in Table 3. MACE occurred in 5 patients (23%). TVR occurred in 2 patients (9%), both of whom underwent revascularization due to pseudoaneurysm formation secondary to coronary perforation. Cardiac tamponade requiring pericardiocentesis occurred in 2 (9%) of the 5 patients who had coronary perforation. No patients required emergency surgery or suffered an in-hospital death.

The main findings of the study were as follows: (1) burr entrapment was observed in 0.69% of the 3195 RAs; (2) most burrs were extracted by strong manual pullback, with no surgical removal required; (3) MACE occurred in 23% of patients; 2 patients required pericardiocentesis, 3 had periprocedural MI, and 2 required TVR. There were no in-hospital deaths or emergency surgeries.

Two mechanisms of burr entrapment have been previously proposed. First, the burr is olive-shaped and has a diamond coating at its distal surface for antegrade ablation; however, the proximal part is smooth without diamonds, which prohibits backward ablation. Therefore, if a burr is advanced beyond a tightly calcified lesion or embedded in a long, angulated, and heavily calcified lesion, it can be entrapped. Moving the burr forward follows the outer curve, and moving it backward follows the inner curve. In particular, if the burr is forced forward with a small burr and inadequate ablation, it is more susceptible to wire bias.

Second, a burr can be advanced beyond a heavily calcified plaque before sufficient ablation, particularly when the burr is pushed firmly at a high rotational speed. During high-speed rotation, frictional heat may enlarge the space between plaques. Meanwhile, the coefficient of friction during motion is less than that at rest, which may facilitate the easy movement of the burr through the calcified lesion without debulking a significant amount of calcified tissue. In this situation, the ledge of calcium proximal to the burr may prevent burr withdrawal, known as the “Kokeshi phenomenon” after the Japanese doll by Kaneda et al.⁷

The incidence of burr entrapment is reported to be 0.4%-0.9%.^3,8,9 The incidence was similar to that in our larger dataset, indicating a low frequency of occurrence.

There are 2 methods for retrieving an entrapped burr: burr removal by deep catheter intubation and expansion of the lesion by balloon angioplasty.³ If a PCI is performed with an 8-Fr guide catheter, a new wire and balloon can be inserted next to the rotablator system. However, if a 7-Fr or smaller guide catheter is used, the rotablator system may be cut off at the advancer, allowing the balloon to be inserted through the same guiding catheter.¹⁰ A double guide is also an effective method for dilating lesions.¹¹ Deep intubation, along with the subsequent pullback of all systems, is effective in concentrating forces on the burr and changing bias. Furthermore, extraction of the drive shaft sheath allows for the insertion of a guide extension catheter.² Even with these methods, if extraction is difficult, surgical removal is necessary. Sumimov et al reported that surgical removal was required in 7 of 18 cases.³ Considering that these 7 cases were all before 2010, the entrapped burr may be removed in most cases by a transcatheter due to more recent advances in devices. However, there is insufficient data to support this assertion. In our study, none of the 22 patients required surgery, and in all cases, the stuck burr could be removed by manual pullback or balloon dilation of the lesion. This may have significant implications in terms of treatment strategies for burr entrapment.

The outcomes of burr entrapment have not been studied in detail because of the lack of systematic studies. Sulimov et al reported 4 cases, among which one required an assist device due to lack of flow, and one developed cardiac tamponade due to coronary perforation. Another patient was asymptomatic but developed elevated troponin.³ In the present study, MACE occurred in 5 cases (23%), but there were no in-hospital deaths.

Limitations. This study has some limitations. First, it was a retrospective observational study, which might have led to selection bias. Manual pullback was performed first; however, the pulling force varied from operator to operator. If it failed, it was up to each operator to decide which other method to use. Second, most entrapped burrs were successfully removed with manual pullback. Therefore, the outcomes of other removal methods remain unknown. Finally, it was possible to use 2 different burr sizes in 1 procedure in Japan, which might have contributed to the choice of burr size and the incidence of stuck burrs. Initially, a smaller burr was often chosen to avoid coronary perforation, which might have caused inadequate ablation of the lesion and burr entrapment.

In our large dataset of 3195 cases who had undergone RA, burr entrapment occurred in 0.69% of cases. Most of these burrs were successfully extracted using a strong manual pullback. Emergency surgery was not required, and no in-hospital deaths occurred. The results provide a treatment approach and prognosis for burr stuck in the use of RA.

From ¹the Division of Cardiology, Shimane University Faculty of Medicine, Izumo, Japan; ²Cardiovascular Medicine, Sapporo Heart Centre, Sapporo Cardiovascular Clinic, Sapporo, Japan

Disclosures: The authors report no financial relationships or conflicts of interest regarding the content herein.

Address for correspondence: Yusuke Morita, MD, PhD, Division of Cardiology, Shimane, University Faculty of Medicine, 89-1, Enya-cho, Izumo, Shimane, Japan 693-8501, Email: morita-y@med.shimane-u.ac.jp