Catheter-supported operations as an alternative to operative procedures are becoming ever more popular in many medical fields; because catheter systems are being continually improved and due to an increase in the number of older and multi-morbid patients, for whom conventional surgical procedures are too risky. Great progress has been made with catheter-based therapies during past years, for example, in the case of heart valve diseases and, in particular, stenosis of the aortic valve. Catheter interventions on the mitral valve are now being more closely focused on. Minimally invasive procedures in the case of valvular heart diseases are therefore also a topic at the coming MEDICA in Düsseldorf, the world's largest medical trade fair with almost 4,800 exhibitors the last time, as well as the MEDICA EDUCATION CONFERENCE (in the Düsseldorf Congress Centre / CCD Süd). MEDICA 2015 will be held from 16 to 19 November, from this year on, running from Monday to Thursday for the first time.
Catheter-based interventions on stenosed aortic valves (TAVI) have an enormous level of importance, especially in Germany. In 2013, already over 10,000 interventions of this kind were performed; in 2008, there were not even 700. The quick increase, however, had led to a controversy between the German Society for Cardiology (Deutsche Gesellschaft für Kardiologie, DGK) and the German Society for Thoracic and Cardiovascular Surgery (Deutsche Gesellschaft für Thorax-, Herz- und Gefäßchirurgie, DGTHG). In particular, the cause of the dispute was a position paper by the Cardiologist Society (Der Kardiologe 2015; 9: 11 – 26). Varying points of view on studies and medical guidelines were formulated in the publication, heart surgeons criticized (Thorac Cardiovasc Surg 2014; 62(8): 639 - 44). The main point of criticism: Expansion of indications of transcatheter aortic valve implantations for patients with an average level of operational risk despite the lack of verified proof of benefit and long-term experience. Another important point of criticism included catheter-based interventions in hospitals without a cardiosurgical department. Cardiologists naturally rejected this criticism. Against the background of this controversy, the German Federal Joint Committee made a decision at the beginning of this year for minimum standards with regard to minimally invasive heart valve intervention (a decision on the type of intervention principally by the cardiac response team; catheter supported interventions should only take place in hospitals with specialised cardiological and cardiosurgical departments). The indication issue was then and is still on the table. Therefore, just a few months later, an improvement of quality assurance in the case of invasive heart therapies and catheter interventions, in particular, when determining indications had been demanded by the DGTHG, the DGK, the Advisory Council on the Assessment of Developments in the Health Care System and the health insurance company, Barmer GEK.
Also on the rise: catheter-based interventions on the mitral valve
Currently, there are many discussions that still are primarily revolving around TAVI while interventions on the mitral valve still remain "in the shadow" of this TAVI debate. Among other things, the reasons have to do with the complex anatomy of the mitral valve and, in comparison, the low amount of verified clinical data. In the case of symptomatic patients with operable severe mitral valve insufficiency (MI), surgical reconstruction is still considered the “golden standard” within the scope of therapy. However, every second or third patient with severe symptomatic mitral regurgitation does not undergo an operation due to accompanying illnesses and advanced age for example. Due to this demographic development, the number of these patients will probably still increase and the "care gap" will get even bigger. "Mitral valve diseases are among the most frequent valvular heart diseases worldwide. And despite the decline in cases of rheumatic mitral stenosis, even in emerging nations, primary and secondary mitral valve insufficiency, at a late age in particular, are becoming increasingly frequent," said the cardiologist, Prof. Hans Reiner Figulla (at the University Hospital of Jena until March 2015) and private lecturer, Alexander Lauten, chief physician and manager of the TAVI programme at Charité Hospital (Herz 2015; 40: 215 – 223).
Several mitral valve systems in development
For this reason, several catheter-based procedures for MI patients are currently being developed. However, both sufficient data deriving from studies as well as extensive clinical experience only exists for the "MitraClip" system (Abbott Vascular): Figulla and Lauten reported that observational studies with several thousand patients have shown initial success rates between 71 and 100 percent. Results of direct comparative studies of the procedure with purely conservative (medicinal) therapy for functional myocardial infarction are still missing. However, randomised controlled trials (COAPT and RESHAPE-HF) have already been initiated.
Among the numerous new systems, there are primarily systems for the reconstruction or correction of insufficient valves, such as procedures for direct and indirect annuloplasty in addition to attempts to seal the mitral regurgitation area or lift the back mitral leaflet. "My hope is that we come just as far with mitral valves as we have come with TAVI in the case of aortic valves. That means that real catheter-based implantations of valve prostheses will become possible both for transapical and for transseptal access. When these valves become prevalent, they may take the same path as TAVIs. This could be initially used in the case of patients who are too ill for an open operation, and then – if the results are good – also in the case of younger and healthier patients,” said the Düsseldorf cardiologist, Professor Malte Kelm at this year’s annual conference of the German Society for Cardiology in Mannheim. However, there must "at least be a sustainable reduction in cardiac failure symptoms beyond procedural safety in randomised studies if a reduction in long-term mortality in the case of functional MI is not possible," wrote Figulla and Lauten.
An example: the Cardioband
Just one example for a highly promising procedure is the so-called Cardioband (Cardioband Annuloplasty System; Valtech Cardio). Really positive, however, intermediate data from 40 patients during the course of a pilot study were presented this year by Professor Karl-Heinz Kuck (Asklepios Klinik St. Georg in Hamburg) at the "Heart Failure Congress 2015" in Seville. In the case of this direct annuloplasty procedure, a band made of synthetic material is attached via a catheter over the femoral vein to the right ventricle of the heart. Via the interatrial septum, it goes into the left atrium of the heart. Then, the band is attached to the connective tissue of the mitral annulus with approximately ten small screws shaped like a crescent moon. Thereby, the precise placement of the synthetic band is important. By pulling on a wire that is wrapped around the band, the opening of the mitral valve is made smaller until the valve leaflets are brought together again. Then, the cardiologists anchor the ends. With time, the synthetic valve ring grows into the tissue.
During the course of the standard procedure, an annuloplasty ring is sewn onto the mitral annulus and then pulled together until the original opening has been reached. In comparison to this, the new procedure brings several benefits for select patients. In this way, heart-lung machines can be done without. In addition, in contrast to surgical procedures on the beating heart, the size of the Cardioband is set with millimeter precision. You can directly see if the valve closes properly again. Kuck said that the procedure was safe and is therefore a good option for any patient who could not have been treated up until this point. In the case of all 40 patients, the implantation was successful and reflux and clinical symptoms were reduced. Cases of death associated with the procedure did not occur. Within 30 days after the operation, in the case of one patient, there was bleeding and, in the case of two patients, renal failure occurred. No participant of the trial suffered from a heart attack, a cardiac tamponade or respiratory failure. The patients (75% men) were 72 years of age on the average, were suffering from moderate to severe functional mitral regurgitation and were at NYHA stage II to IV. The left ventricular ejection fraction was at least at 25 percent. All patients were categorized by cardiologists and a heart surgeon as being high risk patients for conventional surgery.
For older patients, for whom only an insufficient increase in the opening of the valve can be achieved by means of mitral valve valvuloplasty, complete valve replacement systems have been developed, such as the "CardiAQ Valve Technologies System" or the "Tendyne Bioprosthetic Mitral Valve System".
This is "a challenge", but associated with great potential
"Interventional treatment procedures", as has been summarised by Figulla and Lauten, "principally have the potential to replace the surgical therapy procedures for treatment of valvular heart disease established up until now." This also applies to reconstructive interventions on the mitral valve. The anatomy of the mitral valve makes interventions a "challenge", however, the development of new systems for the reconstruction and also implantation is making rapid progress; if sufficient data were present to ensure safety and effectiveness, application of these systems for a larger population of patients is likely and not only in the case of inoperable patients. This was also the prognosis of an author team associated with Doctor Andreas Schaefer from the Heart Centre of the University of Hamburg (EMJ Cardiol 2015; 3 (1): 48-56). According to Figulla and Lauten, these procedures will also be able to be performed economically due to decreasing costs of the implants and a low level of organizational effort (cardiac response team). However: "The valvular interventionalist must have a special education and special proof of their qualifications."
The symposium "Heart Surgery/Cardiology: Transcatheter Valves – Current Trends” (German/English interpreting) is going to be taking place under the direction of Professor Hussein Ince (the Vivantes Medical Centre "Am Urban"/ Berlin) on 16 November as part of the MEDICA EDUCATION CONFERENCE 2015 (Congress Center Düsseldorf / CCD Süd) from 9:00 a.m. - 10:30 a.m. The MEDICA EDUCATION CONFERENCE is being organized by the German Society for Internal Medicine (DGIM) together with Messe Düsseldorf and has been conceived as an advanced training course for all medical fields as well as for representatives from the fields of science and industry.
Author: Dr. med. Thomas Kron, freelance medical journalist (from Worms, Germany)