Lost in circulation

Device complications in complex percutaneous coronary interventions are rare but potentially deadly. Surgical removal is often required. However, an evaluation of surgical therapy beyond case reports is practically not existent.

grew significantly (11% vs 30% for heavily calcified lesions). 2 Currently, these complex lesions represent a significant proportion of PCI procedures performed. 3,4 Therefore, it is well conceivable that this increase in complexity may also lead to a rise in complications including broken, entrapped, or left-in-place guide wires or rotablator devices.
The management of such rare complications is challenging. Three therapeutic options exist: conservative, interventional, or surgical treatment. As entrapped wire fragments and devices in the coronary vessels can cause complications, such as emboli, thrombosis, dissection, and rupture, a conservative strategy is possible only in a small number of cases (14.9%). 5 Some of these potential complications can be managed interventionally and different techniques have been described, [6][7][8][9] but surgical removal, potentially combined with coronary bypass grafting, appears to remain the most common therapy. 5 Despite these recognitions, the literature mainly contains single-case reports on surgical therapy and evaluation of a larger case series is practically not existent.

| METHODS
We prospectively followed all cases of retained guide wires and rotablator devices between January 2015 and December 2019, referred for surgical removal from five different cardiology departments. In addition, we searched our database for such cases between January 2010 and December 2014. The institutional ethics review committee approved the study protocol (reference number: 2020-1749 from 22 April 2020) and waived the need for written informed consent.
Statistical analysis was performed via SPSS Statistics 22 (IBM, Armonk, NY). Data are presented as mean ± standard deviation or percent of patients.
3 | RESULTS Figure 1 shows an example of echocardiographic (panels a, c, and d), fluoroscopic (panels e and f) images of retained wires, as well as the wires themselves postextraction. While from 2015 on, eight cases with lost parts of cardiac interventions were referred, there was not a single case in the 5 years before. gently. In one case, a broken guide wire was an accidental finding during an LVAD implantation. Three of the eight patients were referred to our center for surgical extraction after elective PCI. Table 2 shows the operative characteristics of the patients. The surgical approach was either through complete sternotomy (n = 6) or left-sided minithoracotomy (n = 2). Out of the eight cases, five were operated on-pump (62.5%) and three off-pump (37.5%). An aortotomy F I G U R E 1 Echocardiographic (panels a,c, and d) fluoroscopic (panels e and f) and photographic (panels b and g) images of retained wires in the aorta (panels a-d) and in the right coronary artery (panels e-g). The wires are indicated with a red arrow. The photographs were taken after surgical extraction was necessary in four patients to extract the wires. In six cases, additional bypass grafting was performed. One patient with a lost wire in a perforated right coronary artery developed right heart failure which was not reversible through extraction and bypass grafting. As a consequence, the implantation of a right ventricular assist device was required.
Complete extraction of the foreign bodies was possible in all patients. Table 3 shows the device-type and location in the coronary vessels. The broken devices were mostly located in the right coronary artery (50%), followed by the circumflex artery (37.5%), and diagonal branch (12.5%). In three cases, a vessel was perforated. The devices were mostly remnants of guide wires (n = 4); balloon catheters (n = 3), and in 1 case a rotablator. Interestingly, three out of the eight cases were secondary to chronic total occlusion (CTO) therapy.
All cases of CTO in our group were located in the right coronary artery (RCA). Table 4 shows a description of each removed foreign body as well as its type and brand.
Two patients died due to multiorgan-failure. One was related to the retained device. The implantation of the right heart assist device was not able to prevent the unfavorable outcome. The other patient was a marginal LVAD candidate who developed multiorgan dysfunction unrelated to the retained wire. The lost device here was an accidental finding. All other patients survived and had uneventful postoperative courses. The 1-year follow-up was uneventful for all survivors.

| DISCUSSION
We demonstrate, in this manuscript, that retained foreign bodies from cardiac interventions such as broken guide wires or rotablator approaches. There appears to be a trend toward a rising incidence of such interventional complications possibly reflective of the increased complexity of coronary interventions performed nowadays.
Broken and/or entrapped guide wires, balloons, or other devices are a rare complication of interventional procedures. The incidence of these complications has been reported with 0.1% to 0.2% and may even rise up to 0.2% to 0.4% in cases of rotational atherectomy. [9][10][11][12][13] Currently, about 400 PCI procedures are performed per 100 000 people in Germany. 14 27 Thus, it appears as if there is a significant publication bias for these cases and our ability to assess true outcomes of surgery for these complications is currently very limited.
Our study is so far the largest case series describing the surgical therapy of this interventional complication and to the best of our knowledge, the first prospective one. We observed an increase of the incidence of such patients referred to our department during the last years, while the general number of the other procedures performed remained stable. Our patients were referred from six different cardiology departments and were all performed by different interventional cardiologists, therefore likely excluding a specific human influence as a possible cause. Other authors have also noted that despite technical improvements in the quality of the wires, the incidence of this complication has not decreased over the last decades and may become even higher. 25 Our data show that having an individualized approach is im- factor that needs to be taken into consideration is the duration and the location of myocardial ischemia. In case of suspected acute ischemia, off-pump revascularization has been associated with reduced early mortality and morbidity compared with on-pump. 28 We, therefore, chose an off-pump revascularization strategy whenever possible. However, catheter remnants protruded into the aorta in 50% of the cases and a cardioplegic arrest combined with aortotomy was needed to extract them.
An important procedural aspect here is the fact that protruding wires in the aorta are not easily identifiable fluoroscopically. The protrusion can often not be seen in the fluoroscopic images from the cath-lab and in most cases only the tip of the catheter may be identified (Figure 1, panels e and f). However, the wires protruding from the coronary ostium into the aorta can be easily identified using echocardiography ( Figure 1, panels a, c, and d). Therefore, in all cases of suspected broken and entrapped wires and devices, transoesophageal echocardiography seems to be the diagnostic tool of choice, which best helps in choosing the right operative strategy (on-vs offpump; aortotomy vs aorta no-touch technique).
Although the attempt to remove entrapped wire remnants from the coronary circulation is the preferable option, our case where the wire was an accidental finding during an LVAD implantation proves that surgical therapy is not always necessary and such remnants may remain undetected without causing complications. However, conservative treatment of such patients with systemic anticoagulation and antiplatelet agents appears more appropriate for occluded or smaller distal vessels and early surgical referral may be indicated if

| CONCLUSION
We demonstrate in this study that that retained foreign bodies from cardiac interventions such as broken guide wires or rotablator devices can be completely removed surgically using individualized approaches.
Most of the entrapped devices are located in the RCA. Furthermore, we demonstrate that there appears to be trend toward a rising incidence of these complications possibly reflective of the increased complexity of coronary interventions performed nowadays.

CONFLICT OF INTERESTS
The authors declare that there are no conflict of interests.

AUTHOR CONTRIBUTIONS
HK gathered the data, applied for approval from the ethics com-