At the first Scientific Session of the Annual Meeting of the Swiss Society of Cardiology on June 11, 2014, the focus was on TAVI (transcatheter aortic valve implantation). Cardiac surgeons and cardiologists presented their views on the advantages and disadvantages of the procedure, and the latest Swiss outcome data regarding TAVI were presented.
(ee) Prof. Jürg Grünenfelder, MD, HerzKlinik Hirslanden, Zurich, provided information on TAVI from the surgeon’s perspective. Approximately 10% of patients with aortic stenosis are high-risk or even inoperable. In patients with a thoracic surgery score (STS) above 8 and a Euroscore above 20, TAVI is clearly superior to surgery in terms of morbidity and mortality. But what about the intermediate-risk patients?
According to the German Aortic Valve Registry, mortality is higher in them after TAVI than surgery. “But risk scores do not yield good answers when it comes to the question of TAVI or surgery,” the speaker opined. “Scores don’t take into account factors like frailty, dementia, liver disease, a porcelain aorta, etc. That’s why we need a TAVI risk score.” Two related studies are currently underway.
In all surgical studies to date, access has been by median sternotomy rather than mini-thoracotomy. Prof. Grünenfelder called for their more frequent use, as this could also reduce morbidity and mortality in patients.
Prof. Dr. med. Stephan Windecker, University Hospital Bern, presented the cardiologist’s point of view. He pointed out that TAVI has helped expand indications in previously untreated patients and that TAVI has yielded tremendous technical advances. Results from two randomized trials now show that TAVI offers survival rates at least on par with, or in the most recent trial even superior to, conventional surgical aortic valve replacement. The survival advantage appears to be particularly pronounced in women. Previously expressed reservations regarding the rate of cerebral strokes have been dispelled in recent studies and are due to improved implantation technique and antithrombotic drugs.
Over the long-term up to five years, TAVI prosthetic valves show stable results comparable to conventional surgery. Furthermore, the latest generation of TAVI valve prostheses offers important advances due to near elimination of paravalvular leak and concomitant aortic regurgitation. Most important is the pronounced gain in quality of life that occurs immediately after the intervention.
TAVI registries in Switzerland and elsewhere
The Swiss TAVI Registry(www.swisstaviregistry.ch) was presented by Prof. Peter Wenaweser, MD, University Hospital of Bern. The goal of the registry is to elicit safety and efficacy of TAVI. It has been maintained since February 2011, and since then the number of TAVIs performed has increased month by month. To date, 700 patients with an average age of 81 years and an average Euroscore of 20.2% have been enrolled. In 80%, the procedure was performed with femoral access. The hospital stay lasted an average of 11 days, which the speaker believes is still too long. The 30-day mortality rate is 4.8%, and 12% for emergency procedures. Procedures with transapical access also have a higher mortality. There are no differences in outcome between the different TAVI implants.
Stefan Toggweiler, MD, Lucerne Cantonal Hospital, provided information on figures from international TAVI registries. The first large registry was in Canada, where annual mortality from the second year after surgery was about 10%. A lower annual mortality of 7-10% was shown by the registries of the United Kingdom and Italy. The speaker attributed the different mortality rates in part to the varying risks and comorbidities of the patients treated. For example, the higher the Euroscore of the treated patients, the worse the longevity survival.
In contrast, existing coronary artery disease (CAD), a severely calcified aorta (porcelain aorta) or pacemaker implantation do not influence survival after TAVI – at least not in the medium term. The durability of the implanted valves is good over a period of up to five years; however, long-term results must still be awaited here.
Future developments of TAVI
TAVI is already being performed increasingly in low-risk patients, and this phenomenon will increase in the future, said PD Fabian Nietlispach, MD, University Heart Center, University Hospital Zurich. Two studies are currently underway in this regard: PARTNER 2 and SURTAVI. To meet the new requirements, new devices should fulfill numerous conditions: long shelf life, the possibility of transfemoral implantation under local anesthesia, they should be able to be stored “on the shelf”, and they should not cause obstruction of the coronaries. For self-expanding devices, the “3 R” conditions also apply: recapturable, retrievable, repositionable. Most new devices meet these conditions.
Valve-in-valve TAVI (ViV) was explained by Stéphane Noble, MD, University Hospital of Geneva. This is understood to be TAVI into an existing prosthetic valve. Such procedures are becoming more common as there are more patients who survive valve replacement in the long term and whose bioprostheses degenerate over time. Analyses of data from the global ViV registry (with approximately 550 procedures recorded) show that, on average, these patients have a higher pressure gradient and increased risk of malposition or coronary obstruction. The 30-day mortality averages 7.8%. Of course, it is important to know exactly the dimensions of the original flap (inner diameter). The speaker judged ViV-TAVI to be an attractive alternative to surgery, but there were no comparative studies of repeat surgery yet.
Accesses and closures
Which access should be chosen for TAVI and how is the access closed again? PD Dr. med. Christoph Huber, University Hospital Bern, and PD Dr. med. Giovanni Pedrazzini, Cantonal Hospital Lugano, commented on these questions. Transapical access still requires a thoracotomy until now. Various systems are under development to close the access as with a snap or a screen so that the thoracotomy can be reduced in size. The goal is a completely percutaneous procedure. Such a device does not yet exist, but its development can be expected in the next 2-3 years.
Bleeding complications are relatively common with femoral access, and are more common in women, large diameter catheters (>19 F), and peripheral vascular disease. Because bleeding can be fatal, vascular anatomy must be carefully assessed before a transfemoral procedure; a vessel diameter of at least 18 F is essential. During the procedure, it is essential to puncture at exactly the right point, use the smallest catheter possible (16 or even 14 F), and know how to handle complications – and not hesitate to call the surgeon if necessary.
Conclusion
At the end of the symposium, Prof. Thomas Walther, MD, Bad Nauheim, Germany, summed up. Currently, mortality with TAVI is 3%, and 1% in specialized centers. It is not yet possible to say whether TAVI will be used in other patient groups in the future. The decision for a certain procedure should be based on the individual patient, his symptoms, activities, life expectancy, etc. “TAVI is currently the fastest growing medtech market,” Prof. Walther emphasized. “The interests of industry do not always coincide with the interests of patients. But you can’t let that put pressure on you; you have to look at each patient individually, do a detailed assessment and keep an eye on the study results.”
Source: Annual Meeting of the Swiss Society of Cardiology and the Swiss Society of Cardiothoracic Surgery, Scientific Session on June 11, 2014, Interlaken.
CARDIOVASC 2014, 13(4): 29-30
