Success, Safety, and Efficacy of the Mynx Femoral Closure Device in a Real-World Cohort: Single-Center Experience

Abstract: Background. Femoral artery closure device use following percutaneous cannulation allows earlier mobilization, reduced staff burden, and improved comfort for patients compared with manual compression. The Mynx device (Access Closure, Inc), a novel extravascular closure device, uses a water-soluble non-thrombogenic polyethylene glycol plug. Methods. We report retrospective analysis of success, complication rates, and associated factors in 432 consecutive patients undergoing elective outpatient coronary angiography in a single United Kingdom center. Results. Six Fr sheaths were used in 62.1% and 5 Fr sheaths were used in 37.8%, with 100% successful deployment using a Mynx device. A total of 57.5% of patients were male. In 79.4%, this was the first procedure requiring femoral arteriotomy, while 20.6% had a previous procedure. Overall, 3.2% required conversion to manual compression/FemoStop (St. Jude Medical) due to impending hematoma. In all, 99.5% of patients were discharged on the same day. Confirmed hematoma >5 cm was noted in 0.7% patients, with only 2 patients (0.5%) reporting “any discomfort” during deployment and the same requiring overnight hospitalization. Use of a 6 Fr sheath (compared with 5 Fr) was associated with conversion to manual compression and complications (P<.05), as was valvular heart disease as the indication for angiography (P<.05). Hematoma formation was associated with higher diastolic and mean arterial pressure (107.4 mm Hg vs 99.6 mm Hg; P<.01). There was no increase in complications associated with use of antiplatelet/anticoagulants, previous stroke, myocardial infarction/ischemic heart disease, peripheral vascular disease, diabetes, high body mass index, or previous angiographic procedure. Conclusions. Postangiography use of the Mynx closure device is highly successful, safe, and well-tolerated with a low complication rate, allowing safe same-day discharge. 

J INVASIVE CARDIOL 2016;28(3):104-108

Key words: access-site complications, vascular closure device, Mynx closure device

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The use of femoral artery closure devices following percutaneous cannulation allows for earlier mobilization, reduced staff burden, and improved comfort for patients as compared with manual pressure.¹ However, there is ongoing debate regarding the safety profile of closure devices, in particular the risk of limb ischemia and infection. Among the most widely adopted is the Angio-Seal (St. Jude Medical), which employs a collagen plug and bioabsorbable suture. Angio-Seal reduced the risk of major vascular complications compared with manual compression in several meta-analyses,^2,3 led to shorter hospital stay and improved patient comfort compared with manual compression,⁴ and had overall device success of 97% in >4000 patients undergoing interventional procedures.⁵ However, vascular closure devices such as the Angio-Seal can cause leg ischemia and infection, which seldom occur with manual compression alone, and complications requiring surgical repair are more frequent.⁶ 

The Mynx device (Access Closure, Inc), a novel extravascular closure device, uses a water-soluble non-thrombogenic polyethylene glycol plug. The system gained Food and Drug Administration approval in 2009 and utilizes a self-expanding sealant, which seals the arteriotomy site from outside the vessel without the requirement for any manual compression. More recently, a single observational study comparing the Mynx device with Angio-Seal in femoral catheterization procedures demonstrated significantly reduced frequency of complications requiring surgical repair,⁷ and a separate study reported improved patient comfort compared with Angio-Seal.⁸

Further clarity on the safety and efficacy of the Mynx device following invasive cardiology procedures is required. To this end, we sought to define, in a real-world cohort, the rate of complications from Mynx femoral arteriotomy closure during elective coronary angiography, as well as any patient characteristics that may contribute to such risks.

Methods

All 432 consecutive patients who had undergone diagnostic elective coronary angiography via the femoral artery route followed by arteriotomy closure using the Mynx device between September 2011 and March 2013 were included in the study. All procedures were performed at Stepping Hill Hospital, Stockport, in Greater Manchester, United Kingdom. Data including age, sex, use of antiplatelet therapy or anticoagulants, smoking, and past medical history (stroke, myocardial infarction [MI], baseline eGFR <45 mL/min/1.73 m², body mass index >25, diabetes mellitus, peripheral vascular disease [PVD], hyperlipidemia and statin use, autoimmune disease) were recorded and compared between device failure and non-failure groups. In addition, procedural data including indication for angiography, sheath size, and previous coronary artery bypass grafting were noted. Positive history of hypertension was defined as patients already treated with antihypertensive drugs or previous systolic blood pressure (BP) ≥160 mm Hg or diastolic BP ≥95 mm Hg. Positive history of hypercholesterolemia was defined as total serum cholesterol ≥5 mmol/L. Diagnosis of diabetes mellitus was defined as need for glucose-lowering medications, or previous fasting glucose ≥11.1 mmol/L, or diagnostic response to the oral glucose tolerance test. Active smoking was defined as smoking within the last 3 months. 

Femoral artery access was achieved using a standard Seldinger technique under aseptic conditions. Mynx device size (5 Fr vs 6 Fr) was determined according to the size of vascular sheath used. Intraarterial BP was recorded prior to sheath removal. In the minority of cases where data on intraarterial BP were not available, bedside BP measured using standard sphygmomanometer was noted prior to the procedure. Aortic systolic and diastolic blood pressures were recorded from the arterial pressure trace prior to sheath removal. Mean aortic BP (MABP) was estimated as: diastolic BP + 1/3 x (systolic BP – diastolic BP). Any patients taking warfarin stopped this 5 days prior to the procedure and proceeded with angiography only if international normalized ratio was <1.5 on the day of the procedure. No patients were on low-molecular-weight heparin. Patients taking dual-antiplatelet therapy were allowed to continue such therapies.

Post Mynx deployment care was as per manufacturer recommendations. Briefly, following Mynx device deployment, patients were placed on bedrest for 30 minutes, after which a wound inspection was carried out; if uneventful without signs of bleeding, patients were allowed to ambulate. Access-site complications (hematoma, bleeding, pseudoaneurysm) were documented in addition to device failure and conversion to manual compression or FemoStop prior to patient discharge. 

Mynx efficacy was defined as the ability of the device to achieve full hemostasis. Device failure was defined as failure to stop bleeding after device deployment and conversion to manual compression or FemoStop. Safety of the device was determined by rate of complications; bleeding was defined as a hemoglobin reduction requiring transfusion or requiring surgical intervention, and significant hematoma was defined as >5 cm diameter.⁹

Statistical analysis. Categorical variables were compared between groups using the Fischer’s exact test and continuous variables were compared using Student’s t-test. For all analyses, the criterion for statistical significance was set at P<.05 (two-tailed). 

Results

Of the 432 patients undergoing Mynx closure of femoral arteriotomy following coronary angiography, a total of 34 patients experienced device failure or had subsequent complications. The main outcomes data are summarized in Figure 1. Of note, device failure with conversion to FemoStop or manual compression occurred in 14 patients (3.2%), and hematoma of any size occurred in 16 patients (3.7%), with only 3 of these (0.7%) having confirmed hematoma >5 cm in diameter. No patients required blood transfusion, surgery, or thrombin injection. There were no cases of distal embolization. A clinical diagnosis of groin site infection occurred in 1 patient (0.2%) and required oral antibiotics. Discomfort was reported in 2 patients (0.5%). No pseudoaneurysms were identified in any patients. 

To further investigate the factors contributing to device failure and complications, we compared demographic, clinical, and procedure-related factors between groups (Tables 1, 2, and 3). This revealed no significant relationship between device failure or complication with clinical variables such as age, sex, diabetes, PVD, ischemic heart disease (IHD), MI, stroke, hypertension, previous coronary intervention or angiography, or type of antiplatelet therapy.

Analysis of periprocedural factors demonstrated that complications/device failure were associated with higher use of 6 Fr sheaths (83.3% vs 60%; P<.05). In addition, patients with complications/failure were more likely to be undergoing work-up for valve replacement (40.0% vs 15.9%; P<.05), and less likely to be under investigation for angina (50.0% vs 72.3%; P<.05). Patients who developed a hematoma had significantly higher diastolic and mean arterial BPs compared with those who had no failure or complications (diastolic BP, 82.6 mm Hg vs 75.9 mm Hg [P<.01]; mean BP, 107.4 mm Hg vs 99.6 mm Hg [P<.01]) (Table 3).

Patients undergoing angiography prior to cardiac surgery for valvular heart disease had an increased rate of access-site complications or conversion to manual compression/FemoStop. To investigate this association further, age and comorbidities in this subgroup were compared with patients undergoing coronary angiography for all other indications (Table 4). This showed significantly higher average age in the valvular heart disease group (69.7 years vs 64.0 years; P<.01) and lower statin use (P<.01). Data were not collected on the type of valve or nature of the valve lesion. In addition, patients with valvular heart disease had higher prevalence of stroke and eGFR<45 mL/min/1.73 m², and higher percentage of 6 Fr sheath use (although the latter findings do not reach statistical significance). The decision to use a 6 Fr sheath was made according to operator preference over the study period. Complications and device failure occurred in all operators, and interoperator differences in frequency did not attain statistical significance (data not shown), making it unlikely that operator-specific factors explain the observed difference between 6 Fr and 5 Fr sheaths. 

Discussion

Closure using the Mynx device leads to rapid hemostasis and ambulation,¹⁰ and deployment of the device has recently been shown safe and efficacious in patients undergoing neurovascular procedures.¹¹ In addition, Mynx device use is associated with reduced discomfort⁸ and reduced rate of vascular surgery for arterial access complications compared with the Angio-Seal device.⁷

Conversely, a single study comparing the Mynx closure device with Angio-Seal during percutaneous coronary intervention reported a high failure rate of the Mynx device (conversion to manual compression in 9.2% in a cohort of 238 patients).⁹ The significance of this finding is uncertain given that bleeding risk was higher within the Mynx group (due to increased heparin dose and higher body mass index). However, in this study, Mynx device outcomes included the early stages of operator familiarization with the device (ie, operator learning curve) and heparin use and elevated BMI may be confounding factors. In addition, individual cases of femoral and popliteal artery embolization following Mynx closure have been published,^12-14 and a separate small study of follow-up imaging after Mynx deployment identified intravascular sealant (18%) and pseudoaneurysm (11%) in the 27 patients studied,¹⁵ although this finding was not reproduced in a separate study of repeat angiography following Mynx deployment.¹⁶ 

We report the results of a contemporary analysis of Mynx device use following elective coronary angiography over a 2-year period in a single center treating a real-world patient cohort. To our knowledge, this is the largest database of patients with Mynx deployment in cardiac procedures thus far, and provides new insight into its safety and efficacy.

Our study yielded three main findings. First, the Mynx device was efficacious, with only a small minority requiring conversion to manual compression or FemoStop prior to discharge, and a tiny minority reporting any discomfort following the procedure. Second, deployment of the device appeared safe, with low complication rates, including the “at-risk” subgroups, such as those with elevated BMI or on dual-antiplatelet therapy. Finally, bleeding complications correlated with several correctable risk markers, such as use of higher sheath size and periprocedural BP.¹⁷ This should provide some reassurance that the documented pseudoaneurysms and intravascular sealants observed by Fields et al do not attain clinical relevance in our cohort of patients. 

Our findings agree with a similar analysis of Mynx use in 766 patients undergoing neurovascular procedures where safety and efficacy of the procedure were similarly documented, and complication risk was associated with higher sheath sizes and increasing age.¹¹ In contrast to the findings of Azmoon et al,⁹ a study of Mynx access-site outcomes in 238 patients undergoing PCI, we report a lower rate of device failure (3.2% vs 9.2%) following coronary angiography. There are several possible explanations for this. First, all coronary angiography procedures in our study were elective and diagnostic, with lower use of dual-antiplatelet therapy and without periprocedural anticoagulation. It is noteworthy, however, that in our study the subgroup of patients on dual-antiplatelet therapy experienced a similarly low failure rate. A second explanation is that procedure failure in the previous study may have been related to early learning curve experiences with the device.

An additional finding of our study was that patients undergoing coronary angiography for preoperative work-up of valvular heart disease had increased incidence of access-site complications. While the precise explanation for this effect remains uncertain, our subgroup analysis demonstrates that patients with severe valve lesions had more advanced age and additional comorbidities compared with patients undergoing investigation of angina, differences which may partially explain the increased complication/failure rates. However, a larger and more detailed study (including details on the nature of the valve pathology) would be required to define this relationship in more detail. 

Study limitations. Our study was a retrospective analysis of Mynx femoral arteriotomy closure in a single institution. As such, there were several study limitations. There was no formal follow-up of patients after their procedure or routine imaging of the puncture site. Complications were most frequently identified on the day of the procedure prior to patient discharge. Upon discharge, patients and their relatives were advised to contact the study coordinator if any new swelling, discomfort, bruising, or bleeding was noted. While the number of patients reporting back with complications after discharge was extremely low, there was potential for patients being lost to follow-up in the study.

Conclusion

In summary, the Mynx closure device is safe, efficacious, and comfortable in patients undergoing elective coronary angiography via the femoral artery route. The risk of access-site complications may be further reduced by use of lower sheath sizes (5 Fr vs 6 Fr) and optimization of BP control prior to coronary angiography.

References

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4.    Martin JL, Pratsos A, Magargee E, et al. A randomized trial comparing compression, Perclose Proglide, and Angio-Seal VIP for arterial closure following percutaneous coronary intervention: the CAP trial. Catheter Cardiovasc Interv. 2008;71:1-5.

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6.    Carey D, Martin JR, Moore CA, et al. Complications of femoral artery closure devices. Catheter Cardiovasc Interv. 2001;52:3-7. 

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9.    Azmoon S, Pucillo AL, Aronow WS, et al. Vascular complications after percutaneous coronary intervention following hemostasis with the Mynx vascular closure device versus the AngioSeal vascular closure device. J Invasive Cardiol. 2010;22:175-178.

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11.    Grandhi R, Kanaan H, Shah A, et al. Safety and efficacy of percutaneous femoral artery access followed by Mynx closure in cerebral neurovascular procedures: a single center analysis. J Neurointerv Surg. 2014;6:445-450.

12.    Islam MA, George AK, Norris M. Popliteal artery embolization with the Mynx closure device. Catheter Cardiovasc Interv. 2010;75:35-37. 

13.    Gupta A, Sadiq I, Borer S. Distal embolization from Mynx device. Conn Med. 2012;76:545-548

14.    Rao S, Kaul P, Stouffer GA. Successful aspiration of Mynx vascular closure device sealant that embolized to the popliteal artery. J Invasive Cardiol. 2013;25:E172-E174.

15.    Fields JD, Liu KC, Lee DS, et al. Femoral artery complications associated with the Mynx closure device. AJNR Am J Neuroradiol. 2010;31:1737-1740.

16.    Fargen KM, Velat GJ, Lawson MF, et al. Occurrence of angiographic femoral artery complications after vascular closure with Mynx and AngioSeal. J Neurointerv Surg. 2013;5:161-164.

17.    Dumont CJ. Blood pressure and risks of vascular complications after percutaneous coronary intervention. Dimens Crit Care Nurs. 2007;26:121-127.

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From the ¹Institute of Cardiovascular Sciences, University of Manchester, Oxford Road, Manchester, United Kingdom; and ²Stepping Hill Hospital, Stockport, Greater Manchester, United Kingdom.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Malik reports lecture honoraria from Biosensors, UK. The remaining authors report no conflicts of interest regarding the content herein.

Manuscript submitted July 9, 2015, provisional acceptance given August 10, 2015, final version accepted August 24, 2015.

Address for correspondence: Nadim Malik, MBBS, MA, MD, FRCP, FESC, Stepping Hill Hospital, Stockport, Greater Manchester, United Kingdom. Email: nadim.malik@manchester.ac.uk