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2 decades of structural heart disease
A Cardiology Today Editorial Board Member discusses advances in the treatment of structural heart disease.
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Editor’s Note: Cardiology Today is celebrating its 20th anniversary in 2017. We are reaching out to experts in cardiology for their take on changes in CV medicine since the publication launched in 1997. In this issue, David R. Holmes Jr., MD, MACC, focuses on structural heart disease.
Twenty years ago, we were seeing through a number of initiatives for structural heart disease. There was intense interest in aortic stenosis and mitral stenosis from rheumatic heart disease.
In the late 1980s, balloon valvuloplasty was developed for the treatment of aortic stenosis. It had been used in Europe. There were a series of meetings in France convened by Alain Cribier, MD, in which the advantages of balloon valvuloplasty for aortic stenosis were highlighted. Based upon that, reports were presented in the United States, and a national registry was formed through the NHLBI. About 1,000 patients were enrolled. During that time, we learned a great deal about aortic stenosis and balloon valvuloplasty. Despite the incredible enthusiasm for it, only modest improvement in the initial hemodynamic outcome was achieved. In some patients, that was enough, but we learned, importantly, that improvement did not last very long. We also learned patients who had severe aortic stenosis and were not treated had an incremental mortality increase related to that condition until they were all dead. We learned it was a disease unrelenting in terms of its progress toward poor prognosis.
The initial enthusiasm for balloon valvuloplasty led it to become part of the guidelines. Then, interest in it waned because of its short duration of effect and only modest hemodynamic impact. Over the next several years, it was relegated to very occasional use, certainly never as first-line therapy, often only to improve outcomes in patients undergoing noncardiac surgery. But it was not found to be a satisfactory solution in any way for the vast number of patients.
Dramatic results
Also around that time, balloon valvuloplasty garnered interest as a treatment for mitral stenosis in patients with rheumatic heart disease. We learned more about the hemodynamics involved with that therapy, and there were some dramatic and spectacular results with balloon valvuloplasty in very select cases of patients with severe mitral stenosis. The younger the patient and the less advanced in terms of the pathology, the better. The dramatic improvements in outcome were based on the surgical experience, where the surgeons had been performing dilatation and mitral commissurotomy with excellent results. The technology that became dominant, which replicated the surgical experience, was the Inoue balloon, which was invented and patented by a Japanese surgeon. We were following the surgical approach to mitral commissurotomy using balloon strategies, using different technical approaches. The technology led to improved outcomes, including reduction in mortality, much better improvement in quality of life, and less need for open-heart surgery in selected groups of patients. Worldwide, the technology became very important, because then as now, the incidence of rheumatic heart disease is much higher in the rest of the world than in the U.S.
A lesson that we learned was that there was a substantial number of patients in whom there was an unmet clinical need. That’s been documented in worldwide patient populations, as seen in professional society guidelines such as those from the American College of Cardiology and the European Society of Cardiology, and various regional registries. Since aortic balloon valvuloplasty did not meet the clinical needs of most patients, there was great interest in the development of catheter-based approaches for replacing the valve. A long period of development led to the introduction of transcatheter aortic valve replacement in 2002 by Cribier, who had initially popularized balloon aortic valvuloplasty.
Major expansion
That led to a dramatic expansion in the field of structural heart disease. There has continued to be a dramatic increase in the number of patients recognized to have severe aortic stenosis and a dramatic increase in the number of technologies that could be used to improve what had been temporary results from balloon aortic valvuloplasty to longer-term efficacy in a broader group of patients.
When TAVR was being considered for approval by the FDA in 2011, the ACC and the Society of Thoracic Surgeons pressed the case for a national registry, and CMS agreed. The societies also came up with guidelines for the procedure of TAVR, and CMS implemented them for reimbursement. That led to the Transcatheter Valve Therapy (TVT) registry, which enrolls consecutive patients undergoing commercial TAVR in the U.S. Since that time, there have been more than 90,000 commercial cases entered into the registry.
TAVR has been revolutionary and transformational. We have been able to treat patients who were too high risk to be treated surgically or couldn’t be treated at all. TAVR will migrate to lower-risk patients. It is certainly possible in the relatively near future that TAVR will predominate, and the patients who will be sent for surgical AVR are the ones who don’t qualify for TAVR, rather than vice versa. It will depend on the durability of the transcatheter valves.
A requirement from CMS was that patients had to be considered by a heart team. Although the concept of team-based care has been around for a long time, the heart team approach became central in the area of structural heart disease because of the TVT registry and the CMS mandate.
The use of registries and heart teams are now a requirement to be in the transcatheter aortic, mitral and tricuspid spaces. There are now societal documents identifying the characteristics of a heart team, who needs to be involved with it, how it should be set up, the specific process measures that should be used and the mechanism for certifying them. This has led to a focused approach that includes different stakeholders, including nurses, patients, industry, surgeons, cardiologist, echocardiographers and other paramedical personnel, and has become central for the field of structural heart disease. Going forward, any new technologies that come along will proceed with structural programs that need to be set up in the hospitals with the relevant physician groups.
The TVT registry has expanded to include mitral, tricuspid and pulmonic disease. That will be incredibly important to optimize care and document what we’re doing. We need to focus on optimizing patient selection criteria, procedural performance and overall care. We need to emphasize that institutions and physicians involved in structural heart disease are part of the continuum of care. We need to make sure there is handoff to the primary care physicians, who are the ones evaluating the patients for potential procedures. There has been a diffusion of processes of care.
During the past 20 years, the mindset has shifted from surgeons vs. cardiologists to team-based care. The relationship between surgeons and interventional cardiologists has become much tighter. In the future, people will be able to become certified in structural heart disease, whether they are a surgeon or cardiologist.
Moving forward
There will be new algorithms developed to identify which patients should have procedures and which patients should be reconsidered. As the discipline moves forward, it will be confronted with older and higher-risk patients, and there will have to be very careful decision-making in terms of which patients might benefit and which have an unfavorable risk-benefit ratio. We will be faced with making increasingly important decisions and will need to understand that the ability to perform a procedure is not necessarily the best criterion to do the procedure.
The definition of structural heart disease will continue to grow. It will be more widely applied to include left atrial appendage closure for stroke prevention, patent foramen ovale closure for stroke prevention and other things along those lines. The term “structural heart disease” will become an umbrella for several different groups of diseases, operators and procedures.
– David R. Holmes Jr., MD, MACC
Cardiology Today Editorial Board Member
Mayo Clinic
Past President, American College of Cardiology
Disclosure: Holmes reports no relevant financial disclosures.