Abstract: Objectives. Urgent transcatheter aortic valve replacement (TAVR) is associated with worse short-term outcomes compared with elective TAVR; however, little is known about long-term outcomes or the safety of the minimalist strategy in this setting. This study investigated the short-term and long-term outcomes of urgent TAVR compared with elective TAVR under a minimalist strategy (transfemoral [TF] approach with conscious sedation and no transesophageal echocardiography guidance). Methods. After excluding 2 emergent patients requiring immediate procedures, a total of 474 consecutive patients underwent elective TF-TAVR (396 patients; 83.6%) or urgent TF-TAVR (78 patients; 16.4%). Urgent TAVR was defined as a procedure performed in the same hospitalization in patients emergently admitted due to cardiac arrest, severe acute decompensated heart failure, acute coronary syndrome, or repeated syncopal episodes. Results. A minimalist approach was used in 77 patients (98.7%) undergoing urgent TAVR and in 392 patients (99.0%) undergoing elective TAVR (P=.59). Urgent TAVR had similar procedure-related complications, such as stroke, myocardial infarction, bleeding or vascular complications, and in-hospital mortality compared with elective TAVR (mortality, 1.3% vs 0.8%; P=.51) with no intraprocedural cross-over from conscious sedation to general anesthesia. However, 30-day and 1-year survival rates were reduced in patients undergoing urgent TAVR. After adjustment with baseline and procedural factors, urgent TAVR remained significantly predictive of 1-year mortality (adjusted hazard ratio, 2.26; 95% confidence interval, 1.16-4.23; P=.01). Conclusions. Urgent minimalist TAVR can be safely performed with favorable in-hospital outcomes, while increased 30-day and 1-year mortality rates suggest the importance of appropriate diagnosis and timely treatment of severe aortic stenosis.
J INVASIVE CARDIOL 2019;31(2):E30-E36.
Key words: minimalist approach, severe aortic stenosis. transcatheter aortic valve replacement, urgent procedure
Transcatheter aortic valve replacement (TAVR) is currently accepted as an alternative therapeutic option to surgical aortic valve replacement in severe aortic stenosis (AS) patients who have moderate or higher surgical risk.1,2 Many studies have shown risk factors for short-term and long-term outcomes following TAVR including both cardiac and non-cardiac predictors, such as low left ventricular ejection fraction (LVEF),3,4 chronic lung disease,5,6 chronic kidney disease,5,7,8 and frailty.9,10 Procedural acuity (ie, elective, urgent, emergency, or salvage TAVR) is also one of the short-term risk factors11-14 and is included in the Transcatheter Valve Therapy (TVT) registry model to predict the risk of in-hospital mortality. Patients undergoing urgent TAVR commonly have more dramatic heart failure symptoms and eventually shock as well as other comorbidities compared with those undergoing elective TAVR, which ultimately leads to worse short-term clinical outcomes. While urgent TAVR is often performed in the clinical setting, aiming at minimizing further deterioration of the disease, little is known about its long-term outcomes.15
Minimalist TAVR, defined as a procedure performed under local anesthesia and conscious sedation without transesophageal echocardiography guidance in patients with transfemoral (TF) approach, has been progressively utilized across United States centers with great results.16-18 We hypothesize that the less invasive nature of this approach may deliver additional benefits in patients undergoing urgent TAVR, given the considerable cardiac and non-cardiac comorbidities of this population. As such, this study aimed at investigating the short-term and long-term clinical outcomes of patients undergoing urgent TF-TAVR compared with patients undergoing elective TF-TAVR under a minimalist strategy.
Study population. This is a single-center, retrospective study evaluating the outcomes of urgent TAVR vs elective TAVR. We reviewed 476 consecutive patients who underwent TF-TAVR due to severe native AS between April 2014 and March 2017. Over this period, the minimalist approach was consistently used as a first-line strategy for TF-TAVR. The acuity of TAVR was defined as follows according to the TVT registry model.
Urgent TAVR procedures were performed in the same hospitalization in patients who were emergently admitted due to (1) cardiac arrest; (2) acute decompensated heart failure with New York Heart Association (NYHA) class IV symptoms; (3) acute coronary syndromes; or (4) repeated episodes of syncope. Emergent TAVR procedures were performed in patients who had ongoing, refractory, unrelenting cardiac compromise and were not responsive to any medical therapy. Salvage TAVR procedures were performed for patients who underwent cardiopulmonary resuscitation en route to procedure or prior to anesthesia, or who had ongoing left ventricular assist device or extracorporeal membrane oxygenation to maintain life.
The study was approved by the institutional review board with a waiver of informed consent. Clinical data were collected from the electronic medical record and entered into the REDCap (Research Electronic Data Capture) tool hosted at University Hospitals Cleveland Medical Center.19
Minimalist TAVR procedure. Prior to TAVR, patients were stabilized with medication as much as possible to maintain a supine position for a certain period of time. The minimalist procedure was performed in a standard cardiac catheterization laboratory, under local anesthesia and minimal sedation, without transesophageal echocardiography guidance using commercially available valves, ie, self-expandable valves (CoreValve, EvolutR, and EvolutPro; Medtronic) or balloon-expandable valves (Sapien XT and Sapien 3; Edwards Lifesciences) via TF approach, as previously described by our group.18 Patients who received light sedation were treated with either intravenous diphenhydramine 25 to 50 mg or fentanyl 50 to 100 μg plus midazolam 1 to 5 mg titrated to mild anxiolysis and/or sedation at the discretion of the attending physicians. Patients were in constant communication with the care provider to maintain awareness of what to expect from various stimulating elements of the procedure. All patients were supported as needed to maintain stable hemodynamic parameters with temporary ventricular pacing and intravenous, hemodynamically active agents. Vascular access was obtained percutaneously, followed by double-Proglide sutures (Abbott Vascular). On-site dedicated echocardiography technologists evaluated the implanted valve function as well as potential complications using transthoracic echocardiography. Aortography and hemodynamic measurements were also used post deployment. All patients were transferred to the cardiac intensive care unit for close monitoring after the procedure.
Baseline, follow-up data, and study endpoints. Baseline clinical, echocardiographic, and procedural details were recorded for all patients. Adverse events up to 1 year were obtained from chart review of inpatient admission documentation and outpatient follow-up notes, which were judged according to the Valve Academic Research Consortium (VARC) -2 criteria.20 NYHA classification symptoms were assessed at 30 days and 1 year after TAVR. Transthoracic echocardiography was performed to assess left ventricular (LV) function and implanted valve function immediately and 30 days post procedure. LVEF recovery was assessed by comparing the value of baseline with the value at 30-day follow-up exam among patients with baseline LVEF <50% and no history of myocardial infarction. The primary outcome of this study was all-cause mortality during hospitalization, at 30-day follow-up, and at 1-year follow-up after TAVR.
Statistical analysis. Continuous variables are expressed as mean ± standard deviation or median (interquartile range). Categorical variables are expressed as absolute numbers and percentages. The Student’s t-test or Wilcoxon rank-sum test was used to compare continuous variables, and the Chi-square test or Fisher’s exact test was used to compare categorical variables, as appropriate. Chronological changes in LVEF were compared using paired t-tests. Time-to-event curves for 1-year survival and freedom from rehospitalization based on all available follow-up data were performed using Kaplan-Meier methods and the cumulative probability of the groups was compared by the log-rank test. Cox proportional-hazards regression was used to adjust for the effect of differences in pertinent variables on 1-year all-cause mortality, ie, urgent TAVR, body mass index (BMI), Society of Thoracic Surgeons (STS) score, NYHA classification, chronic obstructive pulmonary disease (COPD), hemoglobin, creatinine, and LVEF. All analyses were two-sided, and significance was judged at P<.05. All statistical analyses were performed with JMP software (SAS Institute).
Patient characteristics. After excluding 2 patients who required emergent/salvage TAVR, a total of 396 patients (83.6%) underwent elective TAVR and 78 patients (16.4%) underwent urgent TAVR. The reasons for urgent TAVR were cardiac arrest in 4 patients (5.1%), acute decompensated heart failure in 64 patients (82.1%), acute coronary syndromes in 2 patients (2.6%), and repeated episodes of syncope in 8 patients (10.3%). Baseline patient characteristics and echocardiographic data are presented in Table 1. Patients in the urgent TAVR group had a greater prevalence of comorbidities, such as chronic dialysis and atrial fibrillation, with a higher level of serum creatinine and a lower level of hemoglobin. The distribution of NYHA classification was also different between the groups; the frequency of class IV was significantly higher in the urgent TAVR group than in the elective TAVR group (10.3% vs 1.5%, respectively; P<.001).
Procedural and in-hospital outcomes. The procedural and in-hospital outcomes for the two treatment groups are presented in Table 2. Balloon-expandable valves were used more often in the urgent TAVR group than in the elective TAVR group (56.4% vs 43.6%, respectively; P=.03). Planned general anesthesia (ie, non-minimalist TAVR) was performed in only a small number of patients (1.3% for urgent vs 1.0% for elective; P=.59), whereas the incidence of emergent conversion to general anesthesia during procedure was low in both groups (0% for urgent vs 1.3% for elective; P>.99). The incidence of other adverse events, such as procedural mortality, major stroke, life-threatening or major bleeding, and major vascular complications, was similar between the groups; however, the urgent TAVR group had higher rates of blood transfusion and acute kidney injury, as well as longer length of postprocedural hospital stay. Of note, in-hospital mortality was similar between the two groups (1.3% for urgent vs 0.8% for elective; P>.99).
Clinical outcomes during 30-day and 1-year follow-up. A total of 53 patients (11.2%) died during the 1-year follow-up period (median, 239 days) after TAVR. Of these, a total of 13 deaths (2.7%) occurred within 30 days (Table 3). At 30 days, urgent TAVR was associated with an increased rate of all-cause mortality and had a tendency toward a higher rate of rehospitalization compared with elective TAVR (9.0% vs 1.5% for mortality [P<.01] and 12.8% vs 7.1% for rehospitalization [P=.09], respectively). Kaplan-Meier curves for freedom from adverse events at 1-year follow-up are shown in Figure 1. Patients with urgent TAVR had a lower survival rate than those with elective TAVR (69.8% vs 86.2%; P<.001), with decreased rates of freedom from cardiovascular mortality, rehospitalization, and combination of mortality or rehospitalization. NYHA symptom classifications improved significantly in both groups at 30 days (P<.001 for both) and throughout the 1-year follow-up (P<.001 for both) compared with baseline. Nonetheless, patients with urgent TAVR tended to be more symptomatic than those with elective TAVR at both 30 days (P=.10) and 1 year (P=.08) (Figure 2). Additionally, although patient number was limited, among patients with LVEF <50% and no previous history of myocardial infarction, there was significant LVEF improvement in the elective TAVR group (n = 32; 33.0 ± 9.2% at baseline vs 40.9 ± 15.1% at 30 days; P<.01), whereas it was not statistically significant in the urgent TAVR group (n = 16; 37.6 ± 9.5% at baseline vs 41.5 ± 10.4% at 30 days; P=.09).
Prognostic factors for all-cause mortality at 1 year. The unadjusted and multivariate-adjusted effects of baseline or procedural variables on 1-year mortality are presented in Table 4. Urgent TAVR, lower BMI, decreased LVEF, and higher STS score were significantly associated with increased mortality at 1 year on univariate analysis. After adjustment using these variables and other clinically important variables, such as NYHA classification, COPD, hemoglobin, and creatinine, only urgent TAVR (adjusted hazard ratio, 2.26; 95% confidence interval, 1.16-4.23; P=.01) and decreased LVEF (adjusted hazard ratio, 0.98 [1% increase]; 95% confidence interval, 0.90-1.00; P=.04) were associated with a higher rate of 1-year mortality.
Urgent minimalist TF-TAVR showed similar rates of procedure-related complications, such as stroke, bleeding, and vascular complications, compared with elective minimalist TF-TAVR, with no increased crossover from conscious sedation to general anesthesia during the procedure. In-hospital mortality rate was low and comparable between the groups (1.3% for urgent vs 0.8% for elective; P>.99); however, urgent TAVR was associated with reduced 30-day and 1-year survival rates, and was a predictor of 1-year mortality on multivariate analysis. These results suggest that although the minimalist approach can be performed safely with favorable in-hospital outcomes in patients undergoing urgent TAVR, these patients have worse long-term outcomes compared with patients undergoing elective TAVR.
Less invasiveness of the minimalist TAVR technique may be a contributor to our favorable outcomes during hospitalization in patients undergoing urgent TAVR. TVT registry data demonstrated that urgent/emergent TAVR was associated with higher rates of intraprocedural and in-hospital mortality.14 However, in the current study, minimalist TAVR could minimize the burden of the procedure in high-risk and elderly patients, especially in terms of the procedure without general anesthesia.17 As the urgent TAVR group had worse baseline cardiac condition, such as worse NYHA class and lower LVEF than the elective TAVR group, patients were more likely to have the possibility of hypotension or hemodynamic instability by the induction of general anesthesia, which leads to a large volume of fluid infusion, initiation of inotropes, and finally unstable condition after the procedure.21 Mechanical ventilation also has a negative effect on maintaining pulmonary function post procedure. Recently, the superiority of conscious sedation to general anesthesia was demonstrated in severe COPD patients undergoing TAVR.22 Of note, no patient undergoing urgent TAVR with a minimalist approach had emergent conversion to general anesthesia, supporting the feasibility and safety of the minimalist strategy.
On the other hand, despite favorable in-hospital outcomes, patients with urgent TAVR had worse clinical outcomes at 30 days and 1 year than those with elective TAVR. Even after a successful procedure, worse baseline characteristics and overall clinical condition may have led to a negative impact on prognosis thereafter. Baseline renal dysfunction is a well-known and consistent risk factor associated with poorer survival across several reports.5,7,8 The presence of anemia, low LVEF, or severe NYHA class3,4,23 has been shown to be a negative prognostic factor after the procedure.24,25 However, after adjustment with these baseline cardiac and non-cardiac factors, urgent TAVR remained significantly predictive of mortality at 1 year. The impairment of cardiac function recovery due to advanced stage of severe AS may affect patient prognosis, together with the functional decline and malnutrition due to long-term heart failure condition or hospitalization. This hypothesis is supported by the results of this study. Patients with urgent TAVR had less LVEF recovery and were more symptomatic at follow-up than those with elective TAVR. In severe AS with chronically increased afterload and LV wall stress, myocardial perfusion is reduced, which causes myocardial ischemia leading to myocyte degeneration and chronic fibrotic changes in the LV.26 Therefore, in the advanced stages of the disease, LV dysfunction persists despite successful valve replacement owing to extensive underlying myocardial fibrosis. This is, in turn, associated with less relief of heart failure symptoms and ultimately poorer prognosis.
The 30-day outcome of urgent TAVR has been reported in a few studies. One report demonstrated a worse survival rate in urgent TAVR,12 which is consistent with the current study, whereas another report showed similar mortality rates between urgent and elective TAVR.27 Patient characteristics differed among studies due to a lack of consistent and established criteria for the indication of urgent TAVR, which warrants further investigation. Until now, 1-year outcomes of urgent TAVR have been unclear. Therefore, this study provides important clinical implications. Although patients who were in extremis with a requirement for emergent or salvage TAVR were excluded from our analysis, there remained patients who failed to derive a survival benefit after the procedure. First of all, it is important to identify the disease (severe AS) and treat patients earlier for the better recovery of cardiac function and quality improvement. In situations where the indication for TAVR is unclear, balloon aortic valvuloplasty (BAV) may be proposed as a bridge or palliative procedure.28,29 BAV can facilitate discharge of patients who are hospital bound, and enables a better comprehension of their functional recovery from debility. Finally, a multidisciplinary approach with palliative care teams and other medical services to provide a comprehensive assessment of baseline frailty, mobility, social support structure, and prognosis of other coexisting medical conditions may be helpful to make a final decision to pursue urgent TAVR in these critically ill patients.
Study limitations. The present study is limited by its retrospective and single-center design. Therefore, the decision for TAVR or other therapies (ie, BAV or continuation of medical therapy) was made by an institutional Heart Team discussion. We performed multivariate analysis in this study, aiming at investigating whether worse outcomes following urgent TAVR could be explained by baseline or procedural characteristics. However, we could not include clinical characteristics that were difficult to quantify, such as advanced stage of severe AS or progressive functional decline. Finally, urgent TAVR under a minimalist approach was performed in a single United States center with high TAVR volume and extensive experience in minimalist TAVR; therefore, our results cannot be immediately generalized.
We conclude that while urgent minimalist TAVR can be safely performed with favorable in-hospital outcomes, it is associated with worse long-term clinical course compared with elective TAVR. These findings emphasize the importance of appropriate diagnosis and timely treatment of severe AS.
- Mack MJ, Leon MB, Smith CR, et al. 5-year outcomes of transcatheter aortic valve replacement or surgical aortic valve replacement for high surgical risk patients with aortic stenosis (PARTNER 1): a randomised controlled trial. Lancet. 2015;385:2477-2484.
- Adams DH, Popma JJ, Reardon MJ, et al. Transcatheter aortic-valve replacement with a self-expanding prosthesis. N Engl J Med. 2014;370:1790-1798.
- Tamburino C, Capodanno D, Ramondo A, et al. Incidence and predictors of early and late mortality after transcatheter aortic valve implantation in 663 patients with severe aortic stenosis. Circulation. 2011;123:299-308.
- Urena M, Webb JG, Eltchaninoff H, et al. Late cardiac death in patients undergoing transcatheter aortic valve replacement: incidence and predictors of advanced heart failure and sudden cardiac death. J Am Coll Cardiol. 2015;65:437-448.
- Ludman PF, Moat N, de Belder MA, et al. Transcatheter aortic valve implantation in the United Kingdom: temporal trends, predictors of outcome, and 6-year follow-up: a report from the UK Transcatheter Aortic Valve Implantation (TAVI) registry, 2007 to 2012. Circulation. 2015;131:1181-1190.
- Mok M, Nombela-Franco L, Dumont E, et al. Chronic obstructive pulmonary disease in patients undergoing transcatheter aortic valve implantation: insights on clinical outcomes, prognostic markers, and functional status changes. JACC Cardiovasc Interv. 2013;6:1072-1084.
- Dumonteil N, van der Boon RM, Tchetche D, et al. Impact of preoperative chronic kidney disease on short- and long-term outcomes after transcatheter aortic valve implantation: a Pooled-RotterdAm-Milano-Toulouse In Collaboration Plus (PRAGMATIC-Plus) initiative substudy. Am Heart J. 2013;165:752-760.
- Yamamoto M, Hayashida K, Mouillet G, et al. Prognostic value of chronic kidney disease after transcatheter aortic valve implantation. J Am Coll Cardiol. 2013;62:869-877.
- Puls M, Sobisiak B, Bleckmann A, et al. Impact of frailty on short- and long-term morbidity and mortality after transcatheter aortic valve implantation: risk assessment by Katz Index of activities of daily living. EuroIntervention. 2014;10:609-619.
- Green P, Arnold SV, Cohen DJ, et al. Relation of frailty to outcomes after transcatheter aortic valve replacement (from the PARTNER trial). Am J Cardiol. 2015;116:264-269.
- Edwards FH, Cohen DJ, O’Brien SM, et al. Development and validation of a risk prediction model for in-hospital mortality after transcatheter aortic valve replacement. JAMA Cardiol. 2016;1:46-52.
- Martin GP, Sperrin M, Ludman PF, et al. Novel United Kingdom prognostic model for 30-day mortality following transcatheter aortic valve implantation. Heart. 2018;104:1109-1116. Epub 2017 Dec 7.
- Pilgrim T, Franzone A, Stortecky S, et al. Predicting mortality after transcatheter aortic valve replacement: external validation of the transcatheter valve therapy registry model. Circ Cardiovasc Interv. 2017;10:e005481.
- Kolte D, Khera S, Vemulapalli S, et al. Outcomes following urgent/emergent transcatheter aortic valve replacement: insights from the STS/ACC TVT registry. JACC Cardiovasc Interv. 2018;11:1175-1185.
- Zahn R, Werner N, Gerckens U, et al. Five-year follow-up after transcatheter aortic valve implantation for symptomatic aortic stenosis. Heart. 2017;103:1970-1976.
- Babaliaros V, Devireddy C, Lerakis S, et al. Comparison of transfemoral transcatheter aortic valve replacement performed in the catheterization laboratory (minimalist approach) versus hybrid operating room (standard approach): outcomes and cost analysis. JACC Cardiovasc Interv. 2014;7:898-904.
- Hyman MC, Vemulapalli S, Szeto WY, et al. Conscious sedation versus general anesthesia for transcatheter aortic valve replacement: insights from the National Cardiovascular Data Registry Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry. Circulation. 2017;136:2132-2140.
- Attizzani GF, Alkhalil A, Padaliya B, et al. Comparison of outcomes of transfemoral transcatheter aortic valve implantation using a minimally invasive versus conventional strategy. Am J Cardiol. 2015;116:1731-1736.
- Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. Research electronic data capture (REDCap) — a metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform. 2009;42:377-381.
- Kappetein AP, Head SJ, Genereux P, et al. Updated standardized endpoint definitions for transcatheter aortic valve implantation: the Valve Academic Research Consortium-2 consensus document. J Am Coll Cardiol. 2012;60:1438-1454.
- Bendel S, Ruokonen E, Polonen P, Uusaro A. Propofol causes more hypotension than etomidate in patients with severe aortic stenosis: a double-blind, randomized study comparing propofol and etomidate. Acta Anaesthesiol Scand. 2007;51:284-289.
- Condado JF, Haider MN, Lerakis S, et al. Does minimalist transfemoral transcatheter aortic valve replacement produce better survival in patients with severe chronic obstructive pulmonary disease? Catheter Cardiovasc Interv. 2017;89:775-780.
- Iung B, Laouenan C, Himbert D, et al. Predictive factors of early mortality after transcatheter aortic valve implantation: individual risk assessment using a simple score. Heart. 2014;100:1016-1023.
- Nuis RJ, Sinning JM, Rodes-Cabau J, et al. Prevalence, factors associated with, and prognostic effects of preoperative anemia on short- and long-term mortality in patients undergoing transcatheter aortic valve implantation. Circ Cardiovasc Interv. 2013;6:625-634.
- Hemmann K, Sirotina M, De Rosa S, et al. The STS score is the strongest predictor of long-term survival following transcatheter aortic valve implantation, whereas access route (transapical versus transfemoral) has no predictive value beyond the periprocedural phase. Interact Cardiovasc Thorac Surg. 2013;17:359-364.
- Hein S, Arnon E, Kostin S, et al. Progression from compensated hypertrophy to failure in the pressure-overloaded human heart: structural deterioration and compensatory mechanisms. Circulation. 2003;107:984-991.
- Landes U, Orvin K, Codner P, et al. Urgent transcatheter aortic valve implantation in patients with severe aortic stenosis and acute heart failure: procedural and 30-day outcomes. Can J Cardiol. 2016;32:726-731.
- Kapadia S, Stewart WJ, Anderson WN, et al. Outcomes of inoperable symptomatic aortic stenosis patients not undergoing aortic valve replacement: insight into the impact of balloon aortic valvuloplasty from the PARTNER trial (Placement of AoRtic TraNscathetER Valve trial). JACC Cardiovasc Interv. 2015;8:324-333.
- Saia F, Marrozzini C, Moretti C, et al. The role of percutaneous balloon aortic valvuloplasty as a bridge for transcatheter aortic valve implantation. EuroIntervention. 2011;7:723-729.
From the 1Valve & Structural Heart Disease Intervention Center, Division of Cardiovascular Medicine, Harrington Heart and Vascular Institute, University Hospitals Cleveland Medical Center, Cleveland, Ohio; 2Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio; 3Interventional Cardiology, Heart Specialists of St. Rita’s, St. Rita’s Medical Center, Mercy Health, Lima, Ohio; 4Division of Cardiovascular Surgery, Harrington Heart and Vascular Institute, University Hospitals Cleveland Medical Center, Cleveland, Ohio; and the 5Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Patel reports honoraria and personal fees from Abbott Vascular, Boston Scientific, and Medtronic. Dr Li serves as a consultant for Medtronic. Dr Bezerra is a consultant for Edwards Lifesciences, Medtronic, and Abbott Vascular. Dr Kalra reports personal fees from Medtronic and Philips. Dr Attizzani is a consultant and proctor for Edwards Lifesciences and Medtronic; consultant for Abbott Vascular. The remaining authors report no conflicts of interest regarding the content herein.
Manuscript submitted September 8, 2018, and accepted September 24, 2018.
Address for correspondence: Yasuhiro Ichibori, MD, PhD, Division of Cardiovascular Medicine, Harrington Heart and Vascular Institute, University Hospitals Cleveland Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106. Email: email@example.com