Author + information
- Tirone E. David, MD∗ ()
- Division of Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, and the University of Toronto, Toronto, Ontario, Canada
- ↵∗Reprint requests and correspondence:
Dr. Tirone E. David, University of Toronto, 200 Elizabeth St. 4N453, Toronto, Ontario M5G 2C4, Canada.
In this issue of the Journal, Tamburino et al. (1) have published a study that compares the clinical outcomes of aortic valve replacement (AVR) with transcatheter aortic valve replacement (TAVR) at 1 year from the OBSERVANT (Observational Study of Effectiveness of SAVR–TAVR Procedures for Severe Aortic Stenosis Treatment) registry, which investigates the management of aortic stenosis (AS) in 93 institutions in Italy. The registry had 7,618 patients with AS (5,707 treated with AVR and 1,991 with TAVR). The investigators excluded 2,150 patients because of combined procedures, porcelain aortas, “hostile thorax,” nonfemoral TAVR, and protocol violation. A total of 4,077 AVRs and 1,391 transfemoral TAVRs were entered into a propensity score analysis to identify patients with similar pre-operative characteristics. The investigators were able to match 650 patients from each group with very similar clinical profiles. These 2 groups had a mean age of 80 years, 60% were women, and they had a predicted procedure-related mortality risk, which was calculated using the logistic EuroSCORE II, of 5.1% for AVR and 4.9% for TAVR. The primary endpoints were death from any cause and major adverse cardiac and cerebrovascular events (MACCE) at 1 year. MACCE were defined as the composite of death from any cause, stroke, myocardial infarction, percutaneous coronary artery intervention, and coronary artery bypass surgery. Secondary endpoints were cerebrovascular accidents, acute myocardial infarction, repeat hospitalization due to cardiac reasons, and acute heart failure.
As would be expected, because the 2 groups of patients were similar in age, sex, and comorbidities, there was no difference in survival or MACCE at 1 year. The effects of the procedure itself will not be apparent until much later, when other factors, such as aortic insufficiency (AI), permanent pacemaker implantation, and primary tissue failure of the bioprosthetic aortic valve become apparent.
There were no surprises in other endpoints, either. The 30-day mortality rate was 3.8% for AVR and 3.2% for TAVR (p = 0.546), and the length of hospital stay was longer for patients who had AVR (12.6 days vs. 8.8 days; p < 0.001). The mean gradients after AVR were slightly higher than those after TAVR, but this was not clinically significant. The incidence of AI (≥grade 2) was lower after AVR than that after TAVR (2% vs. 9.8%; p < 0.001), as was the need for a permanent pacemaker (3.6% vs.15.5%; p < 0.001). There were no differences in stroke rates (2.2% vs. 1.3%), acute myocardial infarction (0.8% vs. 0.5%), and cardiac tamponade (3.9% vs. 4.1%) between the 2 groups.
It can be predicted that the investigators will find no differences in outcomes again when they reexamine these 2 groups of patients at 2 or 5 years. This statement is based on the knowledge of the 5-year results of the PARTNER I (Placement of Aortic Transcatheter Valve Trial) randomized clinical trial on AVR versus TAVR in high-risk patients (Society of Thoracic Surgeons [STS]-predicted mortality risk score of 11.7%.) (2). This study showed a 5-year mortality rate of 62.4% after AVR and a mortality rate of 67.8% after TAVR (p = 0.76) (2). Other important findings in PARTNER I included no cases of primary tissue failure in either group at 5 years, and as demonstrated previously (3), AI had a detrimental effect on survival in patients who had TAVR, but there was no apparent effect on overall survival up to 5 years.
The investigators of this OBSERVANT study identified 650 TAVR patients with a relatively low operative risk score (EuroSCORE II of 4.9%) to compare with AVR. This suggests that our Italian colleagues are adopting TAVR as an alternative to AVR in older patients who are at a lower operative risk than those described in a randomized clinical trial (2). This is not surprising, because both the Edwards SAPIEN (Edwards Lifesciences, Irvine, California) and the Medtronic CoreValve (Medtronic, Minneapolis, Minnesota) devices have been approved for clinical use in Europe since 2007, and one would expect that, as experience with TAVR increases and more data on favorable outcomes become available, more patients will be offered TAVR as an alternative to AVR. This is more evident in Germany, where an ever-increasing number of patients with AS are being treated with TAVR (4). In a recent report from the GARY (German Aortic Valve Registry) study (4), a total of 15,964 patients underwent TAVR in 88 centers in Germany from 2011 to 2013. In 2011, the proportion of isolated AS treated with TAVR was 30%, which increased to 35% in 2012, without an increase in the total number of treated patients (5). This occurred before the results of randomized clinical trials in lower risk patients (SURTAVI [Safety and Efficacy Study of the Medtronic CoreValve System in the Treatment of Severe, Symptomatic Aortic Stenosis in Intermediate Risk Subjects Who Need Aortic Valve Replacement] and PARTNER II) have become available.
Registries such as OBSERVANT and GARY are very important because they capture all patients treated by both methods in multiple hospitals. Unlike many other catheter-based cardiovascular interventions, TAVR has been cautiously introduced and monitored. The role of TAVR in the treatment of AS is likely to continue to expand, and it may become the first choice of therapy if mortality and morbidity associated with the procedure and late outcomes are similar or better than AVR. Several issues need to be resolved before this becomes reality.
AI has a negative effect on survival after TAVR, but no effect on overall survival, which is likely because of sample size and duration of follow-up (2,3). The higher rate of permanent pacemaker implantation after TAVR than after AVR may also affect long-term survival; further follow-up is needed. The durability of bioprosthetic heart valves after AVR is well documented (6,7), but there is limited information on the durability of TAVR (2). PARTNER I showed no primary tissue degeneration up to 5 years of follow-up, but the number of patients at risk was relatively small (2). However, this finding is encouraging and endorses the more widespread use of TAVR. Age is the single most important determinant of primary tissue degeneration after AVR with bioprosthetic valves (6,7). Because TAVR has been used largely in older patients, age may not be as relevant. However, it will become so when used in younger patients with a predicted survival of >5 or 10 years. Thus, it is imperative that registries such as OBSERVANT and GARY continue to collect echocardiographic data on bioprosthetic aortic valve function to determine the durability of devices used for TAVR. We do not know if the xenograft tissue used in TAVR devices will fail due to cusps tearing or because of detachment from the stent, with a consequent increase in AI, or due to stiffening and calcification of the cusps and AS, or a combination of these factors.
Large registries, such as the STS Database, have allowed the development of fairly accurate operative risk calculators for various cardiac operations and of ASCERT (American College of Cardiology Foundation—Society of Thoracic Surgeons Collaboration on the Comparative Effectiveness of Revascularization Strategies) (a long-term survival probability calculator for isolated coronary artery bypass graft surgery) (8). The STS risk calculator and ASCERT can be downloaded through the STS website (9), to estimate late survival after coronary artery bypass graft surgery. The OBSERVANT and GARY registries will allow participants to develop statistical models to determine late survival after treating patients with AS. Once the mathematical effect of each variable that affects survival after AVR and TAVR becomes known, physicians will be better equipped to recommend 1 or the other procedure to treat an individual patient.
Another important issue before considering TAVR in younger patients is aortic valve pathology. Degenerative calcification of the cusps is the most common cause of AS in patients >65 years of age, but a bicuspid aortic valve is the most common finding in younger patients (6). TAVR has been used in selected patients with AS due to bicuspid aortic disease (10), but because of the great variability in pathology of the cusps and root, much more information is needed before its widespread use.
Finally, I commend Tamburino et al. (1) for their efforts in prospectively collecting the OBSERVANT registry data, carefully analyzing the 1-year outcomes, and sharing them with us.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. David has reported that he has no relationships relevant to the contents of this paper to disclose.
- 2015 American College of Cardiology Foundation
- Tamburino C.,
- Barbanti M.,
- D’Errigo P.,
- et al.,
- for the OBSERVANT Research Group
- Mack M.J.,
- Leon M.B.,
- Smith C.R.,
- et al.,
- for the PARTNER 1 Trial Investigators
- Walther T.,
- Hamm C.W.,
- Schuler G.,
- et al.,
- for the GARY Executive Board
- Shahian D.M.,
- O'Brien S.M.,
- Sheng S.,
- et al.
- ↵The Society of Thoracic Surgeons. Available at: http://www.sts.org. Accessed June 17, 2015.