Original Contribution

Randomized Trial of VasoStat Versus TR Band Following Radial Artery Access for Catheterization Procedures

Robert L. Minor, Jr, MD1;  Thomas Maley, RCIS, CPHIMS1;  Diana Jenkins, MSN, RN1; Ya-Huei Li, PhD2

Robert L. Minor, Jr, MD1;  Thomas Maley, RCIS, CPHIMS1;  Diana Jenkins, MSN, RN1; Ya-Huei Li, PhD2

Abstract: Purpose. VasoStat (VS; Forge Medical) is a recently developed radial artery compression device (RCD) producing focused puncture-site pressure.  We compared time to hemostasis and patient experience with VS vs balloon compression with the TR Band (Terumo) in a randomized, prospective trial among subjects undergoing radial catheterization procedures with same-day discharge. Methods. Forty subjects without prior radial access undergoing elective coronary and/or endovascular diagnostic or interventional procedures were randomized to VS or TR Band. Primary outcome was time to hemostasis enabling RCD removal. Secondary outcomes included patient satisfaction measuring subject-reported domains of pain, paresthesia, and swelling, number of device manipulations, and radial patency at follow-up duplex assessment. Hand perfusion index (PI) was also measured prior to radial access, during RCD use, during RCD use with ulnar compression, and after 30 days. Results. VS reduced time to complete hemostasis by 54 ± 20 minutes compared with TR Band (P=.01). Time from RCD application to discharge trended shorter among the VasoStat patients vs TR Band patients (209 ± 13 minutes vs 254 ± 22 minutes, respectively; P=.09). VS required fewer RCD manipulations (P=.04). Mean patient discomfort score was 2.7 with VS and 6.1 with TR (P=.04). Change from baseline in hand PI was similar at all time points. After 30 days, ultrasound detected no radial artery occlusion and no difference in radial artery peak systolic velocities (57 cm/s with VS vs 50 cm/s with TR; P=.85). Conclusion. Both RCDs achieved hemostasis enabling same-day discharge. VS had significantly shorter time to hemostasis with fewer device manipulations and increased patient-reported comfort.  

J INVASIVE CARDIOL 2021;33(2):E84-E90. Epub 2021 Jan 21.

Key words: hemostasis, radial compression devices, radial artery occlusion


Over 1.6 million cardiac catheterization procedures are performed each year in the United States, comprising approximately 700,000 diagnostic and 900,000 percutaneous coronary intervention (PCI) procedures.1,2 The traditional route of arterial access for cardiac catheterization has been the femoral artery. Drawbacks of femoral artery access include risks of local hematoma, retroperitoneal hemorrhage, femoral pseudoaneurysm, and arteriovenous fistula. Because these risks are minimal or absent when using the radial artery for access, the transradial approach is increasingly utilized for diagnostic and interventional catheterization procedures.3 Recent randomized trials have shown radial artery catheterization is associated with fewer puncture-site complications compared with transfemoral access as well as reduced 30-day all-cause mortality in emergent PCI for ST-segment elevation myocardial infarction (STEMI).4-6 For PCI in the United States, these benefits have contributed to a significant growth in radial access, which now is used in nearly 50% of cases.7 Cost savings using a transradial approach for PCI combined with same-day discharge are substantial and exceed $3500 per patient.8

Radial compression devices (RCDs) are routinely utilized following transradial catheterization to achieve puncture-site hemostasis. Most current RCDs consist of a plastic band secured around the patient’s wrist with hook and loop fastener (Velcro), which applies pressure to the volar surface through an inflatable balloon integrated within the band. These balloon-based RCDs must be incrementally inflated to produce hemostasis and then deflated to enable removal. These devices apply compression to a large area of the patient’s wrist (typically 6-10 cm2 surface area), exceeding the size of the radial artery puncture site. This relatively large area of vascular compression may result in impairment of hand perfusion during normal clinical use of this device9 and can cause significant pain in the wrist and hand.10 

An alternative approach to RCD design was utilized in the development of the VasoStat device (Forge Medical), which was recently introduced in the United States and Japan. The VasoStat uses a ratcheting, vertical compression mechanism aligned over the radial arterial puncture site to provide more focused pressure than circumferential band-balloon RCDs. Preliminary experience has suggested that the VasoStat may achieve hemostasis more efficiently than non-selective compression bands.11 

The purpose of this study was to compare time to hemostasis and other outcomes relevant to patient experience between a traditional RCD, the TR Band (Terumo Medical), with the VasoStat in a randomized, prospective trial including patients with no prior radial artery catheterization undergoing planned same-day discharge.

Methods

Study design and population. This investigator-initiated study randomized subjects with no prior radial access undergoing elective coronary or endovascular diagnostic or interventional procedures to hemostasis using one of two RCDs following sheath removal: VasoStat or TR Band. Over a 7-month period, subjects were prospectively enrolled to 1 of 2 Food and Drug Administration (FDA)-cleared radial artery hemostasis devices, a focused-compression device (VasoStat) or a balloon-compression device (TR Band) (Figure 1). Subjects were randomized in a 1:1 allocation using block permutation and opaque sealed envelopes opened immediately prior to catheterization, with random permuted block sizes to eliminate investigator anticipation of allocation. The study was approved by an accredited independent institutional review board (Western Institutional Review Board, Olympia, Washington; clinicaltrials.gov identifier NCT04163471). All subjects provided written informed consent. 

Transradial catheterization and hemostasis device application. Diagnostic or interventional coronary or peripheral catheterization was performed through 5 or 6 Fr sheaths in all subjects. A standard radial artery antispasm/anticoagulation mixture was administered into the radial artery in all subjects, consisting of 200 µg of nitroglycerin, 2.5 mg of verapamil, and 5000 U of heparin. Interventional procedures received additional heparin as needed to maintain an activated clotting time of >300 seconds. Following each procedure and immediately prior to sheath removal, an additional 200 µg of nitroglycerin and 2.5 mg of verapamil were administered through the sheath. The assigned RCD (VasoStat or TR Band) was then applied to the puncture site following sheath removal according to randomization, and patent hemostasis technique was used for each device. 

To enable objective determination of time to hemostasis, puncture-site assessments were performed by catheterization laboratory nurses every 15 minutes, beginning 45 minutes post RCD placement. During puncture-site assessments, nurses were given clinical discretion to remove the RCD based on objective criteria showing lack of puncture site oozing or bleeding. For the VasoStat, this involved a 2-step release of the integrated ratcheting mechanism. For the TR Band, progressive balloon deflation was performed in 1-2 mL increments. To minimize observer bias within the study, the nursing team was not instructed to attempt removal of either device prior to a preset time point.

Following securement of either study device, the nursing team recorded each instance of device manipulation until hemostasis-enabling device removal. These manipulations involved uncoupling of a ratchet position of the plunger of the VasoStat during loosening prior to removal, and incremental balloon deflation of the TR Band.

The primary study endpoint was time to complete hemostasis enabling RCD removal. Because all subjects were enrolled with an intent-to-treat endpoint, secondary endpoints included time from RCD application to same-day discharge.

Hematoma at any time during RCD use was managed with device repositioning or tightening as required. Since hematomas were elliptical in shape, hematoma size was recorded as the transverse dimensions times pi (π).

Age, sex, and weight were recorded for each subject, in addition to the proportion of subjects with a history of diabetes (defined as requiring insulin or oral hypoglycemics), hypertension (requiring one or more antihypertensives), hyperlipidemia (requiring statins or other therapy), peripheral arterial disease (claudication, prior surgical bypass, or endovascular therapy), cerebrovascular disease (prior carotid endarterectomy, carotid stent, ischemic stroke, or transient ischemic attack), or end-stage renal disease (on hemodialysis or peritoneal dialysis). Patient demographics are summarized in Table 1.

Secondary endpoints. Patient satisfaction was assessed following device removal using Likert scales for patient-reported domains of pain, paresthesia, and swelling, each scaled from 0-10 in increasing severity. Scores of the three domains were added to determine a cumulative patient discomfort score. 

Patient hand perfusion was measured using a previously validated metric of perfusion index (PI), which is the ratio of the pulsatile blood flow to the non-pulsatile or static blood in peripheral tissue.12-14 The PI represents a non-invasive measure of hand perfusion that can be continuously obtained from certain models of pulse oximeters. In this study, PI was measured using a portable pulse oximeter device (Masimo Corporation). PI was measured after 30 seconds of equilibration at the following time points in each subject: (1) at baseline immediately prior to radial artery catheterization and sheath placement; (2) at baseline after at least 60 seconds of ulnar compression; (3) immediately after sheath removal with the assigned RCD in place; (4) following RCD application with at least 60 seconds of sustained manual ulnar artery compression; and (5) after 30 days at outpatient follow-up visit concurrent with duplex ultrasound assessment. Percent changes in PI at each time point were compared with baseline PI.

Statistical analyses. Baseline subject characteristics shown in Table 1 and procedural characteristics between the two RCD groups in Table 2 were compared with t-tests for continuous variables and Fisher’s exact test for categorical variables. Time to complete hemostasis and other continuous variables, such as time to hemostasis, were compared using unpaired t-tests. Univariate and multivariate logistic regression analyses were used to assess the effect of clinical and procedural covariates on time to hemostasis. PI measurements were compared using Mann-Whitney tests, and relative changes in PI with the Kruskal-Wallis test. All analyses were performed with SAS software, version 9.4 (SAS Institute) or Stata (Stata Corporation). 

Sample size. The sample size of the study was estimated using a two-sample test of proportions to detect a 40% difference in the time to hemostasis enabling RCD removal with a power of 80% and a type I (alpha) error of 5%. A minimum of 40 subjects (20 in each arm) needed to be randomized. 

Results

Hemostasis-enabling device removal and same-day discharge were achieved in all subjects. Time to hemostasis and time to discharge following initial RCD application are shown in Figure 2. The VasoStat subjects had a mean time to hemostasis of 145 ± 36 minutes vs 199 ± 77 minutes with the TR Band, which is a difference of 54 ± 20 minutes (P=.01). Among interventional cases, the VasoStat device resulted in a 77-minute reduction in time to hemostasis vs the TR Band (P=.02). Time from RCD application to same-day discharge was also shorter among the VasoStat subjects vs the TR Band (209 ± 13 minutes vs 254 ± 22 minutes, respectively), although this difference was not significant (P=.09). 

To further explore the effect of RCD and other variables on time to hemostasis, logistic regression was used. A series of univariate analyses were performed using time exceeding mean duration to hemostasis as the dependent variable. Independent variables were RCD type, age, sex, sheath size, heparin dose, interventional procedure (vs diagnostic) and antiplatelet therapy (≥1 of aspirin, clopidogrel, or ticagrelor at the time of radial artery catheterization). The results of univariate analysis are shown in Table 3. RCD type was most predictive of longer times to hemostasis; subjects assigned to TR Band had an 11-fold higher odds of longer time to hemostasis (P<.01). Interventional procedures had a 4-fold higher odds compared with diagnostic procedures (P=.03) and antiplatelet therapy was associated with 4-fold higher odds compared with no antiplatelet therapy (P=.04). Heparin dose was weakly predictive, with doses ≥10,000 U having 3 times higher odds of prolonged time to hemostasis (P=.21). Age, sex, and sheath size were not predictive of time to hemostasis.

To determine the interaction between these variables influencing time to hemostasis, the variables significant in univariate analysis were entered into the multivariate model. Heparin dose ≥10,000 U was also included in the multivariate model to explore whether interactions with other variables existed, even though it was not statistically significant in univariate analysis. As shown in Table 4, only RCD allocation remained predictive of increased time to hemostasis, with the TR Band having 12-fold higher odds of longer time to hemostasis vs the VasoStat device (P<.01).

Patient comfort, expressed as a cumulative score encompassing patient-reported domains of pain, paresthesia, and hand swelling, found a mean discomfort score of 2.7 among VasoStat patients vs 6.1 among TR Band patients (P=.04).

The VasoStat device required a mean of 3.7 manipulations vs 4.4 with the TR Band (P=.04); 12/20 patients (60%) in the TR Band group required 5 or more device manipulations vs 5/20 patients (25%) in the VasoStat group (Figure 3).

Hematomas occurred in 4/20 patients (20%) in the TR Band group vs 3/20 patients (15%) in the VasoStat group (P>.99); hematomas were significantly larger in mean cross-sectional area with the TR Band vs the VasoStat (22 cm2 vs 10 cm2, respectively; P=.02). Two patients re-bled at their puncture site following TR Band removal vs none of the VasoStat subjects (P=.49). Rebleeding in both TR Band subjects was managed with manual compression; this additional time was not added to the cumulative time to device hemostasis in the TR Band group. 

Changes in hand perfusion compared with baseline are summarized in Figure 4. Prior to RCD application, ulnar compression produced transient decreases of 25%-26% in hand perfusion in both groups. Following sheath removal, the VasoStat device was associated with increased hand perfusion from baseline by 37% and the TR Band by 24% (P=.73); these changes were reversed by ulnar compression, which produced a 49% decrease from baseline with the VasoStat and a 42% decrease with the TR Band (P=.56). 

All subjects returned for follow-up duplex ultrasound and hand perfusion assessment at the cardiology clinic within 60 days of the catheterization procedure (mean time to follow-up, 57 days in the VasoStat group vs 47 days in the TR Band group; P=.80). No radial artery occlusion (RAO) was identified in either group at follow-up. Peak systolic velocity in the radial artery was 59 cm/s in the VasoStat subjects vs 57 cm/s among the TR Band subjects (P=.08). Mean increase in hand perfusion from precatheterization baseline was 18% in VasoStat patients vs 19% in TR Band patients (P=.98). 

Discussion

Radial access for coronary and peripheral catheterization continues to gain widespread adoption in the United States, enabling hospitals and health systems to implement same-day discharge programs to further improve patient satisfaction and operational efficiency for elective patients. From 2009 to 2013, same-day discharge for elective PCI tripled in data from New York and Florida.15 The cost savings realized to a hospital with 1000 elective PCIs/year adopting a transradial and same-day discharge program has been calculated to exceed $1M annually with a 30% adoption rate and $1.7M with a 50% adoption rate.8 These trends also provide an opportunity to refine and optimize existing protocols for effective and patient-centered puncture-site hemostasis. The present trial was designed as a feasibility study to compare the VasoStat, an RCD using focused pressure over the puncture site, with the TR Band, a conventional circumferential band device using a broad-based surface of balloon compression, to evaluate whether differences existed in time to hemostasis and patient experience. 

The VasoStat resulted in a 54-minute shorter time to complete hemostasis enabling RCD removal compared with the TR Band (P=.01). In univariate and multivariate regression, VasoStat (vs TR Band) remained the most predictive variable of shorter time to hemostasis among other factors, including age, sex, sheath size, antiplatelet therapy, and interventional (vs diagnostic) procedures. Heparin doses differed by a mean of 1700 U higher among the TR Band group related to a higher number of interventional cases within the group; despite this difference, heparin was not predictive of time to hemostasis in either univariate or multivariate models. Manual compression achieves radial hemostasis significantly faster than balloon compression;16 we attribute the shorter time to hemostasis with the VasoStat to the focused compression surface over the radial artery, which more closely resembles the physics of manual compression. The findings of the present study are consistent with the randomized trial by Safirstein et al, who also showed significantly shorter time to hemostasis with the VasoStat following transradial PCI compared with the TR Band.17 Further evaluation within a larger randomized trial is warranted, as consistently shorter hemostasis times could improve patient satisfaction, realize significant cost savings, and reduce demands on nursing puncture-site monitoring in higher-volume radial-based cardiovascular centers. These considerations also align with the current growth in same-day discharge for elective PCI in the United States8,15 and Canada.18

Both RCDs transiently decreased hand perfusion by 25%-26% from baseline during clinical use, although these differences were not significantly different between devices. These findings are similar to those of vanLeeuwen et al,9 who found PI (as measured by laser Doppler perfusion imaging) decreased by 32% during TR Band use following radial artery sheath removal. Notably, the use of transient ulnar compression during RCD use in the present study produced substantial decreases in hand perfusion with both devices. This finding is discordant with prior findings, which suggest an adaptive mechanism may exist with radial and ulnar flow to enable an increase in blood flow to the hand when the ulnar artery is compressed during RCD use.19

No RAOs were detected in either arm of this study. Duplex measurements of radial artery velocities were similar in both groups at follow-up. The lack of RAO in the current study may be due to meticulous use of patent hemostasis technique and radial cocktail administration in both RCD groups, although RAO could have been expected to occur in a larger clinical trial. In a recent retrospective series of 249 arterial access sites with hemostasis achieved with the VasoStat, the majority (67%) of which were radial using sheath sizes of 4-7 Fr, RAO occurred in 2 patients (0.8%) at ultrasound follow-up. Both patients had radial artery recanalization after short courses of clopidogrel and aspirin, and rivaroxaban, respectively.11 In a meta-analysis of RAO, Rashid et al analyzed 66 studies, most using the TR Band; the RAO rate by ultrasound assessment was 6.7% within 24 hours and 6.2% beyond 7 days.20 

Radial access has been shown to be a major factor in patient comfort and satisfaction following catheterization procedures21,22 and is now included as a metric for cardiac catheterization laboratory accreditation by the American College of Cardiology.23 Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) scores are used by Centers for Medicare and Medicaid Services (CMS) for all Medicare-approved hospitals in the United States to assess patient satisfaction and enable facility comparison.24 Moreover, HCAHPS scores affect hospital reimbursement25 and account for 30% of a hospital’s total performance score.26 Additional metrics within the HCAHPS system affecting facility reimbursement include assessment of patient safety; among these are perioperative hematoma. The VasoStat was associated with higher patient-reported comfort compared with the TR Band (P=.04). Hematoma formation was less common and smaller in size among the VasoStat subjects compared with the TR Band group (P=.02). This study is too small to determine the extent to which improved patient satisfaction and lower hematoma risk affected facility reimbursement; however, this potential association would be interesting to explore in a larger longitudinal study.

Study limitations. This study has several limitations inherent to a single-center, randomized trial; sample size was small and therefore subject to a type I error. Interventional procedures (coronary/peripheral) were not balanced between the study groups, as subjects were enrolled with a plan for possible intervention on the basis of diagnostic catheterization findings. Blinding of RCD allocation was not possible, as the study protocol required continued visualization of the radial puncture site by catheterization laboratory and study personnel.

Conclusion

Both RCDs achieved hemostasis, enabling device removal and same-day discharge. The VasoStat device resulted in a significantly shorter time to hemostasis, with fewer device manipulations and increased patient-reported comfort. Hematomas were less frequent and smaller in size among the VasoStat patients. Transient changes in hand perfusion occurred to a similar degree with both devices during device use, but exceeded baseline measurements at follow-up.

References

1. Fanaroff AC, Zakroysky P, Dai D, et al. Outcomes of PCI in relation to procedural characteristics and operator volumes in the United States. J Am Coll Cardiol. 2017;69:2913-2924.

2. Masoudi FA, Ponirakis A, de Lemos JA, et al. Trends in U.S. cardiovascular care: 2016 report from 4 ACC National Cardiovascular Data Registries. J Am Coll Cardiol. 2017;69:1427-1450.

3. Valle JA, Kaltenbach LA, Bradley SM, et al. Variation in the adoption of transradial access for ST-segment elevation myocardial infarction: insights from the NCDR CathPCI registry. JACC Cardiovasc Interv. 2017;10:2242-2254.

4. Jolly S, Yusuf S, Cairns J, et al. Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (RIVAL): a randomised, parallel group, multicentre trial. Lancet. 2011;377:1409-1420.

5. Romagnoli E, Biondi-Zoccai G, Sciahbasi A, et al. Radial versus femoral randomized investigation in ST-segment elevation acute coronary syndrome. J Am Coll Cardiol. 2012;60:2481-2489.

6. Ferrante G, Rao S, Juni P, et al. Radial versus femoral access for coronary interventions across the entire spectrum of patients with coronary artery disease: a meta-analysis of randomized trials. JACC Cardiovasc Interv. 2016;9:1419-1434.

7. CathPCI Database, American College of Cardiology-National Cardiovascular Data Registry (NCDR), August 2019 Data. Available at https://ncdr.com. Accessed on January 14, 2021.

8. Amin AP, Pinto D, House JA, Rao SV, et al. Association of same-day discharge after elective percutaneous coronary intervention in the United States with costs and outcomes. JAMA Cardiol. 2018;3:1041-1049.

9. van Leeuwen MAH, van der Heijden DJ, Hollander MR, et al. ACRA perfusion study. Circ Cardiovasc Interv. 2019;12:e007641.

10. Ul Haq MA, Rashid M, Kwok CS, Wong CW, Nolan J, Mamas MA. Hand dysfunction after transradial artery catheterization for coronary procedures. World J Cardiol. 2017;9:609-619.

11. Barrette LX, Vance AZ, Shamimi-Noori S, et al. Nonfemoral arterial hemostasis following percutaneous intervention using a focused compression device. Cardiovasc Intervent Radiol. 2020;43:714-720. Epub 2020 Feb 10.

12. Genzel-Boroviczeny O, Strotgen J, Harris A, Messmer K, Christ F. Orthogonal polarization spectral imaging (OPS): a novel method to measure the microcirculation in term and preterm infants transcutaneously. Pediatric Research.2002;51:386-391.

13. Hager H, Reddy D, Kurz A. Perfusion index-a valuable tool to assess changes in peripheral perfusion caused by sevoflurane? Anesthesiology. 2003;99:A553.

14. Zaramella P, Freato F, Quaresima V, et al. Foot pulse oximeter perfusion index correlates with calf muscle perfusion measured by near-infrared spectroscopy in healthy neonates. J Perinatol. 2005;25:417-422.

15. Agarwal S, Thakkar B, Skelding KA, Blankenship JC. Trends and outcomes after same-day discharge after percutaneous coronary interventions. Circ Cardiovasc Qual Outcomes. 2017;10:e003936.

16. Petroglou D, Didagelos M, Chalikias G, et al. Manual versus mechanical compression of the radial artery after transradial coronary angiography. JACC Cardiovasc Interv. 2018;11:1050-1058.

17. Safirstein JG, Elfandi A, Reid N, Clark TWI. Randomized trial of radial hemostasis using focused vs balloon compression devices. J Invasive Cardiol. 2020;32:169-174. Epub 2020 Apr 24.

18. Madan M, Bagai A, Overgaard CB, et al. Same-day discharge after elective percutaneous coronary interventions in Ontario, Canada. J Am Heart Assoc. 2019;8:e012131.

19. Pancholy S, Bernat I, Bertrand OF, Patel TM. Prevention of radial artery occlusion after transradial catheterization. JACC Cardiovasc Interv. 2016;9:1992-1999.

20. Rashid M, Kwok C, Pancholy S, et al. Radial artery occlusion after transradial interventions: a systematic review and meta-analysis. J Am Heart Assoc. 2016;5:e002686.

21. Amin AP, Crimmins-Reda P, Miller S, et al. Novel patient-centered approach to facilitate same-day discharge in patients undergoing elective percutaneous coronary intervention. J Am Heart Assoc. 2018;7:e005733.

22. Biasco L, Pedrazzini GB, Araco M, et al. Evaluation of a protocol for same-day discharge after radial lounge monitoring in a southern Swiss referral percutaneous coronary intervention centre. J Cardiovasc Med. 2017;18:590-595.

23. American College of Cardiology: cardiac cath lab accreditation program. Available at https://accreditation.acc.org. Accessed on January 14, 2021.

24. Centers for Medicare & Medicaid Services (CMS), Health and Human Services. Medicare program: hospital outpatient prospective payment and ambulatory surgical center payment systems and quality reporting programs. Fed Regist. 2016;81:79562-79892.

25. Mazurenko O, Collum T, Ferdinand A, Menachemi N. Predictors of hospital patient satisfaction as measured by HCAHPS: a systematic review. J Healthc Manag. 2017;62:272-283.

26. Elliott MN, Beckett MK, Lehrman WG, et al. Understanding the role played by Medicare's patient experience points system in hospital reimbursement. Health Affairs. 2016;35:1673-1680.


From the 1Billings Clinic Heart and Vascular at Community Medical Center, Missoula, Montana; and 2Billings Clinic, Billings, Montana.

Funding: This study was investigator-initiated and supported by the Department of Collaborative Science and Innovation at the Billings Clinic, Billings, MT. Forge Medical provided indirect support through payment of institutional review board submission fees, but was not involved in the design or conduct of the study.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Minor reports consultant and advisor income from Medtronic (unrelated to the present study). The remaining authors report no conflicts of interest regarding the content herein.

Manuscript accepted July 9, 2020.

Address for correspondence: Robert L. Minor, Jr, MD, Billings Clinic Heart and Vascular at Community Medical Center, 2827 Fort Missoula Road, Missoula, MT 59804-7408. Email: RMinor@BillingsClinic.org

/sites/invasivecardiology.com/files/articles/images/E84-E90%20Minor%20JIC%20Feb%202021%20wm.pdf