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J Thorac Cardiovasc Surg 2009;137:167-173
© 2009 The American Association for Thoracic Surgery
Evolving Technology |
a Division of Cardiac Surgery, St Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
b Division of Cardiology, St Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
Received for publication May 14, 2008; revisions received July 28, 2008; accepted for publication August 31, 2008. * Address for reprints: Jian Ye, MD, Division of Cardiothoracic Surgery, St Paul's Hospital, Room 489, 1081 Burrard St, Vancouver, BC, Canada, V6Z 1Y6. (Email: jye{at}providencehealth.bc.ca).
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Abstract |
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Methods: Between October 2005 and January 2007, 26 patients (13 female) underwent transcatheter transapical aortic valve implantation with either 23- or 26-mm Edwards Lifesciences transcatheter bioprostheses. All patients with symptomatic aortic stenosis were declined for conventional aortic valve replacement because of unacceptable operative risks and were not candidates for transfemoral aortic valve implantation because of poor arterial access. Clinical and echocardiographic follow-up was performed before discharge and at 1, 6, and 12 months. Data from the 17 patients who survived over 12 months were used for comparisons of the baseline and follow-up results.
Results: The mean age was 80 ± 9 years, and the predicted operative mortality was 37% ± 20% by using logistic EuroSCORE and 11% ± 6% by using the Society of Thoracic Surgeons Risk Calculator. Valves were successfully implanted in all patients. Six patients died within 30 days (30-day mortality, 23%), and 3 patients died from noncardiovascular causes after 30 days (late mortality, 12%). Among patients who survived at least 30 days, 12-month survival was 85%. There were no late valve-related complications. New York Heart Association functional class improved significantly. The aortic valve area and mean gradient remained stable at 12 months (1.6 ± 0.3 cm2 and 9.6 ± 4.8 mm Hg, respectively).
Conclusion: Our 1-year clinical and echocardiographic outcomes suggest that transapical transcatheter aortic valve implantation is a viable alternative to conventional aortic valve replacement in selected high-risk patients.
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Introduction |
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However, because a considerable number of elderly patients with symptomatic severe aortic stenosis have significant comorbidities, open-heart AVR with CPB can be associated with an unacceptable perioperative mortality and morbidity. Therapeutic options for these patients are limited, and neither medical therapy nor balloon valvuloplasty offers survival benefit. Over the past several years, the development of minimally invasive transcatheter valve implantation has been explored.2-13 A percutaneous alternative was first developed in an animal model by Andersen and colleagues.2,14 Subsequently, a number of groups pursued various approaches to transcatheter aortic valve implantation (AVI).2-5,14-18 It was not until a decade after it was initially proposed that the feasibility of percutaneous AVI was demonstrated in human subjects by Cribier and associates7,8 using a transvenous transseptal approach. Subsequently, we described a retrograde procedure using percutaneous femoral artery access.10 We reported the first successful transcatheter transapical AVI through a left minithoracotomy and the apex of the left ventricle without CPB in human subjects in 200611,12 and then our initial experience of transapical transcatheter AVI without CPB in our first 10 patients.19,20 We have now completed a 12-month clinical and echocardiographic follow-up in our first 26 patients who underwent transapical transcatheter AVI without CPB. |
Materials and Methods |
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Patients
Patients who were accepted for transcatheter AVI were initially assessed for suitability for percutaneous transfemoral AVI. Patients underwent preoperative work-up, including coronary and aortofemoral angiography and transthoracic echocardiography (TTE). Transesophageal echocardiography (TEE) was performed when the diameter of the aortic annulus could not be easily measured from the TTE images or a more accurate measurement was required. Transapical AVI was recommended if aortofemoral angiographic analysis revealed unfavorable anatomy of the aorta, iliofemoral arteries, or both for the transfemoral approach.
Prosthetic Valve Implantation
The procedure of transapical transcatheter AVI was described in detail in our previous publications.11,19,20 Briefly, the procedure was performed after achievement of general anesthesia in an operating room. The apex of the left ventricle was identified by using a portable C-arm fluoroscopy and exposed through an approximately 5-cm anterolateral minithoracotomy and a small pericardial incision. Two paired orthogonal U-shaped sutures with pledgets were placed into the myocardium and passed through tensioning tourniquets. Epicardial pacing wires were used for rapid ventricular pacing during aortic valvuloplasty and deployment of the prosthesis.
Heparin was administered to achieve an activated clotting time of greater than 250 seconds. Using fluoroscopic, aortographic, and TEE imaging, balloon valvuloplasty and then deployment of the bioprosthesis were performed during rapid ventricular pacing to minimize ventricular ejection without CPB (Figure 1 ). We used balloon-expandable transcatheter bioprostheses (SAPIENTM THV; Edwards Lifesciences, Inc, Irvine, Calif). Twenty-three–millimeter bioprostheses were used in 6 patients, and 26-mm bioprostheses were used in 20 patients. CPB was not used in any patient. Patients were maintained on aspirin indefinitely and clopidogrel for at least 1 month. Warfarin was initially used in some patients who underwent transapical AVI, but this was abandoned because of the frequency of bleeding intolerance in these elderly patients.
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Echocardiograms were reviewed by our senior echocardiographers. Intraoperative and immediate postoperative acute myocardial infarction was defined by electrocardiographic criteria, whereas acute myocardial infarction during follow-up was defined as an increase of troponin T levels associated with clinical symptoms, electrocardiographic evidence of infarction, or both. Procedure-related major bleeding is defined as significant blood loss caused by a difficult apical hemostasis and a requirement for blood transfusion intraoperatively. Postoperative bleeding was defined as any significant blood loss requiring surgical intervention, significant blood transfusion (>2 units), or both.
Statistical Analysis
Data are presented as the mean ± standard deviation. All echocardiographic parameters and New York Heart Association (NYHA) class were matched data from 17 patients who survived for longer than 12 months. The 2-way analysis of variance model was used to compare echocardiographic parameters (aortic valve area, mean transaortic pressure gradient, aortic insufficiency, left ventricular ejection fraction, and mitral regurgitation) and NYHA class between different time points. The paired t test was used to compare the left ventricular mass index at the baseline level and at 6 to 12 months after the procedure. The Kaplan–Meier method was used to generate survival curves. The statistical analyses were performed with the SAS (version 9.1.3) statistical software package.
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Results |
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In the 17 survivors the majority of the patients (near 80%) had NYHA class III and IV heart failure symptoms before the procedure. Significant early improvement in functional class was achieved in most patients, and more than 80% had NYHA class I or II heart failure symptoms at the 1-month follow-up. Some continued improvement in functional class was observed during 6 to 12 months of follow-up (Figure 3, F).
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The left ventricular ejection fraction increased after AVI from a mean of 56% ± 13% preoperatively to 63% ± 9% at 12 months (Figure 3, E), although this was not statistically significant. The increase in ejection fraction was mainly as a result of an improvement in the patients with preoperative left ventricular dysfunction. Three patients with severe left ventricular dysfunction had more impressive improvement in ejection fraction from 33% ± 3% preoperatively to 57% ± 10% at 12 months of follow-up.
Moderate-to-severe mitral regurgitation was present at baseline in 59% of the 17 survivors. A reduction in mitral regurgitation was observed immediately after the procedure, and 23% of the 17 survivors had moderate or severe MR at 12 months (Figure 3, D).
Valvular or paravalvular aortic insufficiency was determined by means of echocardiography. No survivors had aortic insufficiency greater than mild (mild in 47% and trivial/none in 53% of survivors) at 1 month after the procedure. The degree of aortic insufficiency remained unchanged from 1 to 12 months (Figure 3, C). Clinical hemolysis was not observed.
In 9 survivors left ventricular mass indices were available at baseline and at 6 to 12 months of follow-up. In these patients the left ventricular mass index decreased from 133 ± 56 g/m2 preoperatively to 104 ± 32 g/m2 at 6 to 12 months after the procedure, but there was no statistical difference (P = .123).
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Discussion |
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A considerable number of potential surgical candidates have significant comorbid conditions, and cardiac surgery with CPB might pose risks that are unacceptable to them or their physicians.29,30 According to the STS database (1998–2001), surgical AVR carries a rate of serious complication or mortality of 16.8%. Although the mortality of selected octogenarians undergoing cardiac surgery compared with that of younger patients is only moderately increased, their morbidity is clearly higher. Reported mortality for septuagenarians and octogenarians undergoing primary isolated AVR ranges from 6.6% to 16.7%, whereas reported operative morbidity, including atrial fibrillation, in elderly patients (>70 years old) after AVR with or without coronary artery bypass was up to 64% to 76%.22,31,32
Transcatheter AVI is an evolving surgical procedure developed in part to deal with an increasing preoperative risk profile of the patient population with symptomatic aortic valve disease. The clinical feasibility of the transapical transcatheter AVI has been well documented.11,12,19,20,33 This report represents the longest follow-up data on transapical transcatheter AVI in a relatively large number of patients (n = 26) being followed clinically and echocardiographically for at least 12 months. These patients were judged to be poor candidates for routine cardiac surgery by 2 independent surgeons because of an unacceptably high risk of operative mortality and particularly morbidity. These patients were also declined for transcatheter transfemoral AVI, mainly because of severe aortic or peripheral vascular disease, or had failed transfemoral AVI. The estimated operative mortality was 37% ± 20% by using the logistic EuroSCORE and 11% ± 6% by using the STS Risk Calculator. Our observed 30-day mortality in this initial cohort of patients was 23%, which is higher than STS estimates. However, the prediction models are based on retrospective analysis of patients who underwent conventional AVR, which contains a few patients with risk profiles similar to those of our patient cohort. Many risk factors that were observed in our patients are not well reflected by these scoring systems, such as end-stage liver disease, prolonged preoperative hospital stay, general deconditioning, immobility because of other medical conditions, significant abnormalities of other valves, severity of peripheral vascular and aortic disease, and end-stage lung disease. These risk factors are also the major contribution to the early and late mortality and morbidity after transapical transcatheter AVI, which would explain our relatively high 30-day operative mortality. Nine of our 26 patients had EuroSCOREs of greater than 50%, several patients had end-stage lung and liver diseases, and the majority of our patients had severe systemic vasculopathy. We believe that patient selection has a direct effect on operative mortality. Furthermore, the learning curve of the novel procedure would also have an effect on our operative mortality because the operative mortality in our last 30 patients decreased to 13% (unpublished data). Early major complications are observed in 9 patients, of whom 6 died within 30 days. Early operative mortality could be reduced significantly by preventing perioperative complications, such as bleeding and pneumonia, and appropriate patient selection. The causes of late mortality (11.5%) are noncardiac, including pneumonia in 2 patients and cancer in 1 patient. There were no late valve-related or procedure-related complications in this cohort of patients during the 12 months of follow-up.
The transapical approach for transcatheter AVI is reliable, with acceptable operative risks and favorable clinical and echocardiographic outcomes in the majority of these very high-risk patients. Postoperative recovery, length of hospital stay, and late survival are largely dependent on preoperative comorbidities and general health conditions. The procedure provides immediate relief of symptoms related to aortic stenosis, such as angina, presyncope, or syncope, and continued improvement in heart failure symptoms during the 12 months of follow-up. The majority of survivors (94%) had NYHA class I or II heart failure symptoms at 12 months after the procedure. Most of the survivors were very satisfied with their cardiac conditions and living independently at follow-up.
Transcatheter bioprosthetic valve function appeared excellent, without evidence of structural valve deterioration/dysfunction or inadequate fixation at 12 months after implantation. Trivial-to-mild paravalvular regurgitation was common immediately after deployment of the prostheses but remained stable at 12 months. More significant paravalvular regurgitation resulting from incomplete deployment of the bioprosthesis can be effectively reduced by repeat balloon dilation.34 This has been demonstrated in 2 patients. However, repeat balloon dilation is not effective in reducing significant paravalvular regurgitation caused by suboptimal positioning of the bioprosthesis, which was seen in 1 patient.
Concomitant severe mitral regurgitation or significant coronary artery disease in the presence of severe aortic stenosis is generally considered an indication for a combined surgical procedure with an attendant increase in operative mortality and morbidity, particularly in patients with advanced age and significant comorbid conditions. In the present series 59% of patients had moderate-to-severe mitral regurgitation. A decrease in mitral valve regurgitation and an increase in left ventricular function after transapical AVI suggest that a conservative approach to coexisting mitral valve regurgitation might be a reasonable approach in selected patients.
Coronary artery disease was present in 69% of patients. Although prior coronary artery grafting and angioplasty had been performed in the distant past in 31% and 19%, respectively, many patients had residual nonrevascularized coronary disease. One patient underwent prophylactic preprocedural angioplasty, and 1 patient had a combined minimally invasive coronary artery bypass and transapical AVI. No early and late myocardial infarction in this cohort of patients was observed during 12 months of follow-up, which suggests that aggressive interventions for moderate coronary artery disease before the transapical procedure might not routinely be necessary.
The risk of perioperative stroke appeared low because it was observed only in 1 (3.8%) patient during 12 months of follow-up. The low incidence of stroke, particularly with the transapical approach, is likely a result of (1) avoidance of passing a large catheter through the aortic arch and ascending aorta, as occurs during transfemoral retrograde AVI; (2) an antegrade, rather than retrograde, approach to the calcified aortic valve; or both. Obstruction of the coronary ostium by a bulky calcified native valve, the transcatheter bioprosthesis, or both has been documented, but the incidence appears infrequent.10 We observed this complication in 1 patient in this series. Preoperative assessment of the amount of the calcification, location of the bulky calcification, location of the coronary ostia, and anatomy of the aortic root might reduce the risk of this fatal complication.
Device embolization is a documented complication35 but was not observed during early and late follow-up in this cohort undergoing transapical AVI. Theoretically, better coaxial positioning and stabilization of the device during deployment can be achieved with the transapical approach because of a short straight line from the apex to the annulus, relative to the transfemoral approach. Given the small numbers treated to date, this remains to be evaluated. We believe that the experience of surgeons, interventional cardiologists, and echocardiographers plays a major role in avoiding this complication.
In summary, our 12-month clinical and echocardiographic outcomes suggest that transapical transcatheter AVI is a viable alternative to conventional open-heart AVR in selected high-risk patients with symptomatic severe aortic stenosis. Although excellent structural and hemodynamic stability of the bioprosthesis is demonstrated at 12 months of follow-up, in vivo long-term durability of the transcatheter bioprosthesis remains to be determined. Both the technology and techniques in transapical transcatheter AVI continue to evolve, and we are all in a process of learning who will be the most appropriate candidates. Conventional open-heart AVR remains the first-line therapy for symptomatic severe aortic stenosis.
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Footnotes |
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Drs Webb, Munt, and Cheung are consultants to Edwards Lifesciences, Inc, Irvine, Calif. Dr Webb has also received some financial support for his research from Edwards Lifesciences, Inc.
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References |
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80 years: results from the National Cardiovascular Network. J Am Coll Cardiol 2000;35:731-738.This article has been cited by other articles:
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  S. Bleiziffer, D. Mazzitelli, A. Opitz, I. Hettich, H. Ruge, N. Piazza, and R. Lange Beyond the short-term: Clinical outcome and valve performance 2 years after transcatheter aortic valve implantation in 227 patients J. Thorac. Cardiovasc. Surg., February 1, 2012; 143(2): 310 - 317. [Abstract] [Full Text] [PDF]
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 O. O. Alli, J. D. Booker, R. J. Lennon, K. L. Greason, C. S. Rihal, and D. R. Holmes Jr Transcatheter Aortic Valve Implantation: Assessing the Learning Curve J. Am. Coll. Cardiol. Intv., January 1, 2012; 5(1): 72 - 79. [Abstract] [Full Text] [PDF]
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A. Colli, R. D'Amico, J. Kempfert, M. A. Borger, F. W. Mohr, and T. Walther Transesophageal echocardiographic scoring for transcatheter aortic valve implantation: Impact of aortic cusp calcification on postoperative aortic regurgitation. J. Thorac. Cardiovasc. Surg., November 1, 2011; 142(5): 1229 - 1235. [Abstract] [Full Text] [PDF]
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 R. Lange, S. Bleiziffer, N. Piazza, D. Mazzitelli, A. Hutter, P. Tassani-Prell, J.-C. Laborde, and R. Bauernschmitt Incidence and treatment of procedural cardiovascular complications associated with trans-arterial and trans-apical interventional aortic valve implantation in 412 consecutive patients Eur J Cardiothorac Surg, November 1, 2011; 40(5): 1105 - 1113. [Abstract] [Full Text] [PDF]
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 S. H. Ewe, V. Delgado, A. C. T. Ng, M. L. Antoni, F. van der Kley, N. A. Marsan, A. de Weger, G. Tavilla, E. R. Holman, M. J. Schalij, et al. Outcomes After Transcatheter Aortic Valve Implantation: Transfemoral Versus Transapical Approach Ann. Thorac. Surg., October 1, 2011; 92(4): 1244 - 1251. [Abstract] [Full Text] [PDF]
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J. Higgins, J. Ye, K. H. Humphries, A. Cheung, D. A. Wood, J. G. Webb, and S. V. Lichtenstein Early clinical outcomes after transapical aortic valve implantation: A propensity-matched comparison with conventional aortic valve replacement J. Thorac. Cardiovasc. Surg., August 1, 2011; 142(2): e47 - e52. [Abstract] [Full Text] [PDF]
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A. W. Cheung, R. Gurvitch, J. Ye, D. Wood, S. V. Lichtenstein, C. Thompson, and J. G. Webb Transcatheter transapical mitral valve-in-valve implantations for a failed bioprosthesis: A case series J. Thorac. Cardiovasc. Surg., March 1, 2011; 141(3): 711 - 715. [Abstract] [Full Text] [PDF]
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A. W. ElBardissi, P. Shekar, G. S. Couper, and L. H. Cohn Minimally invasive aortic valve replacement in octogenarian, high-risk, transcatheter aortic valve implantation candidates J. Thorac. Cardiovasc. Surg., February 1, 2011; 141(2): 328 - 335. [Abstract] [Full Text] [PDF]
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F. Dagenais, P. Mathieu, D. Doyle, E. Dumont, and P. Voisine Moderate Aortic Stenosis in Coronary Artery Bypass Grafting Patients More Than 70 Years of Age: To Replace or Not to Replace? Ann. Thorac. Surg., November 1, 2010; 90(5): 1495 - 1500. [Abstract] [Full Text] [PDF]
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M. Arnold, S. Schulz-Heise, S. Achenbach, S. Ott, A. Dorfler, D. Ropers, R. Feyrer, F. Einhaus, S. Loders, F. Mahmoud, et al. Embolic Cerebral Insults After Transapical Aortic Valve Implantation Detected by Magnetic Resonance Imaging J. Am. Coll. Cardiol. Intv., November 1, 2010; 3(11): 1126 - 1132. [Abstract] [Full Text] [PDF]
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G. Bruschi, P. Fratto, F. De Marco, J. Oreglia, P. Colombo, L. Botta, A. Cannata, A. Moreo, B. De Chiara, F. Lullo, et al. The trans-subclavian retrograde approach for transcatheter aortic valve replacement: Single-center experience J. Thorac. Cardiovasc. Surg., October 1, 2010; 140(4): 911 - 915.e2. [Abstract] [Full Text] [PDF]
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 R. Gurvitch, D. A. Wood, E. L. Tay, J. Leipsic, J. Ye, S. V. Lichtenstein, C. R. Thompson, R. G. Carere, N. Wijesinghe, F. Nietlispach, et al. Transcatheter Aortic Valve Implantation: Durability of Clinical and Hemodynamic Outcomes Beyond 3 Years in a Large Patient Cohort Circulation, September 28, 2010; 122(13): 1319 - 1327. [Abstract] [Full Text] [PDF]
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S. Bleiziffer, H. Ruge, J. Horer, A. Hutter, S. Geisbusch, G. Brockmann, D. Mazzitelli, R. Bauernschmitt, and R. Lange Predictors for New-Onset Complete Heart Block After Transcatheter Aortic Valve Implantation J. Am. Coll. Cardiol. Intv., May 1, 2010; 3(5): 524 - 530. [Abstract] [Full Text] [PDF]
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 J. Rodes-Cabau, J. G. Webb, A. Cheung, J. Ye, E. Dumont, C. M. Feindel, M. Osten, M. K. Natarajan, J. L. Velianou, G. Martucci, et al. Transcatheter Aortic Valve Implantation for the Treatment of Severe Symptomatic Aortic Stenosis in Patients at Very High or Prohibitive Surgical Risk: Acute and Late Outcomes of the Multicenter Canadian Experience J. Am. Coll. Cardiol., March 16, 2010; 55(11): 1080 - 1090. [Abstract] [Full Text] [PDF]
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