Transcatheter transformation

September 12, 2018 0 By S Harachand

S Harachand

Transcatheter procedures are taking centre-stage in cardiovascular medicine as a less-invasive alternative to open heart surgeries that involve splitting open the rib cage to get access to the vital organ.

Replacement of heart valves via catheterisation leaves a very small, often unrecognisable, scar at access points, such as upper thighs, compared to deep sternal wounds in traditional heart surgeries. Surgical replacement of aortic valve accounts for about 10-15% of all sternotomy, experts say.

“There’s an explosion of technology happening in interventional cardiology. Interventionists now have minimally invasive options for many conventional surgeries, But the traditional techniques of surgery take time to change,” observes Dr Praveen Varma PK, Professor and Head of the Department, Cardiovascular & Thoracic Surgery, Amrita Institute of Medical Sciences (AIMS), Kochi.

What makes transcatheter procedures even more attractive is the faster recovery time. The patient can leave the hospital within just two days instead of a minimum of two weeks of hospitalization, followed by months-long mandatory rest, in the case of open surgery.


TAVR – The harbinger of change

Transaortic valve replacement or TAVR is one such procedure gaining wide currency among cardiologists and patients worldwide.

TAVR is considered a boon for patients suffering from severe aortic stenosis (AS) with prohibitive surgical risk. Quite often, aged patients with severe AS are turned away deeming unfit for surgical aortic valve replacement (SAVR) citing frailty, co-morbid conditions or a poorly functioning left ventricle as reasons.

TAVR has already been established as the preferred approach in patients facing a higher risk for SAVR, supported by evidence generated from large, randomised studies such as Placement of AoRTic TraNscathetER Valve Trial using Sapien valve (Partner) and the CoreValve US pivotal trials. Prospective randomised data from the Partner B cohort studies demonstrated that TAVR is superior to medical therapy in inoperable patients.

Clinical outcomes from trials in intermediate risk patients using Sapien 3 valve (Partner IIS3i) indicated significantly lower death rates. The occurrence of stroke also fell drastically to 1% at 30 days in comparison with 4.4% in surgery patients over the same period.

Five-year follow-up data from Medtronic’s CoreValve US pivotal NOTION (Nordic Aortic Valve Intervention Trial) studies showed similar rates of all-cause mortality and superior hemodynamic performance for TAVR compared to surgery.


Rise and rise of TAVR

TAVR has made remarkable progress since it was started in 2002. The procedure was originally approved for transcatheter aortic valve replacement as an alternative option to SAVR for patients with native aortic stenosis whose risk of death or severe complications from surgery is high. In 2016, the USFDA expanded the TAVR indication for Sapien 3 transcatheter heart valve (THV) to patients who are at intermediate surgical risk of death or complications. Later, in 2017, the FDA again approved an expanded use of Sapien 3, made by Edwards Lifesciences LLC, as a valve-in-valve treatment. Valve-in-valve procedures offer an alternative to repeat surgery since the replacement valve is inserted inside the failing surgical bioprosthetic valve through a patient’s blood vessel or a small cut in a patient’s chest.

In the US, TAVR took a big leap to nearly 40,000 procedures in 2017 from less than 5,000 cases five years ago. Similarly, the centres registered for doing TAVR procedure in the US also grew five-fold during the same period.

TAVR is widely accepted by interventionists in the US and a lot of them want to do the procedure, said Dr Tyrone J Collins, Director of Interventional Cardiology, Ochsner Clinic, New Orleans, USA. “I think most doctors would be willing to do TAVR or send their patients for TAVR. But probably, if I had to guess only 10% are actually doing it. It’s a small number.”

One of the major hurdles that come in the way of rapid expansion of TAVR in the US is the set of norms set by the US FDA for hospitals and physicians. The hospitals are required to have a certain volume of valve surgery performed. And the surgeons and cardiologists have to work together.

A team of physicians is required to perform the procedure, Dr Collins added.


Heart Team: A multi-disciplinary approach

The European Union granted CE marking for Medtronics’ CoreValve system way back in 2007. Currently, TAVR is performed in AS patients who are at high risk with a logistic EuroScore of more than 20%, as well as in those who are contraindicated to surgery.

The recently published European guidelines on valvular heart disease recognise the achievements around TAVR. The guidance puts the multi-disciplinary Heart Team — comprising cardiologists, cardiac surgeons, anaesthetists, elderly specialists and non-medical cardiac care specialists — at the centre of the decision process with regard to the choice of the surgical/interventional treatment. These Heart Teams are seen to operate best in Heart Valve Centres, in which comprehensive diagnostic and therapeutic options are provided to the highest standards. The treatment provided in these centres of excellence can be adjusted to individual patient needs, which should consequently improve results.

Unsurprisingly, the US and EU top the chart for the number of TAVRs performed. Some estimates show that TAVR outnumbered surgical valve replacement in the US in 2016.

In India, TAVR is catching up with more and more cardiologists and cardiac surgeons coming forward to update themselves with the new modality of treatment.

“The therapy is gaining momentum exponentially due to many cardiologists and surgeons wanting to adopt the therapy. But expertise in the form of structurally trained specialists in this therapy are a minority,” opines Dr A B Gopalamurugan, Director for Cardiac Services, HeartTeam India, SIMS Hospital, Chennai.


Skill-gap – A concern in India?

The majority of operators in India have not gone through the training but perform these procedures with the help of proctors. India Valves Heart Team started by Heart Valve Foundation of India, a national forum for transcatheter valve therapy, is a dedicated effort to impart structured training in this discipline, Gopalamurugan explained.

Started in 2017, India Valves Heart Team is a virtual heart team concept. It is a team of skilled transcatheter valve therapy experts on call, who will travel across India helping physicians adopt the therapy in their own place. The team can be contracted by any centre with the amenities to deliver the TAVR procedures and simultaneously train specialists.

The number of AS requiring valve replacement is steadily on the rise in India. Nearly one-third of severe AS cases diagnosed go untreated.

According to Dr Gopalamurugan, there are at least a thousand heart centres in India having the basic infrastructure required for TAVR, including a catheter laboratory and an on-site cardiac surgery. But what is lacking are the protocols, procedures and training for TAVR sessions.


From coronary to peripheral

Not all the experts in the field, however, seem to share the view that skill shortage is such a big problem in India today. “There was a dearth of skilled vascular interventionists in India, not in coronary interventionists. But now, since they are acquiring peripheral vascular skills in addition to coronary skills, the dearth is becoming less and less,” avers Dr. (Prof.) N.N. Khanna, Coordinator of Cardiology, Cathlab & Vascular Services, Indraprastha Apollo Hospitals, New Delhi & President of International Society of Endovascular Specialists (ISEVS – Indian Chapter).

Pointing out the huge turnout at the 10th Asia Pacific Vascular Intervention Course (APVIC) that concluded recently in New Delhi, Dr Khanna said the need for the interventionists to get themselves acquainted with this technology is felt much more today than in earlier days.

“Last year, APIC had 1,000 delegates and 50 international faculties. This year it has gone up to 1,380 delegates and 82 international faculties. As far as the workshops are concerned, they went from 8 last year to 18 for 10th APVIC,” adds Dr Khanna, who is also the Chairman of Asia Pacific Vascular Society.

Even though the acceptance level of TAVR is quite good among Indian clinicians, it is not getting transformed into practice. Less than 200 cases a year are done in the entire country, when the need is almost 2 lakh procedures in a year. The prime reason, according to him, is the cost. In India, a TAVR procedure can cost around Rs 26 lakhs,whereas surgical valve replacement costs only Rs 2.5 lakhs. In other words, TAVR is ten times costlier than SAVR.

The cost factor, however, is likely to improve in the future, as was seen in the case of coronary stents and angioplasty.


Factors limiting TAVR spread

It is true that less-invasive transcatheter replacements are safer and hassle-free. They involve less trauma and the patients need lesser time to recover. They also give outcomes which are similar, if not better, to surgery as shown by extensive clinical studies.

However, it remains to be seen whether transcatheter valve replacements, especially TAVR, will become the standard of care in place of surgery.

One of the major factors limiting the widespread adoption of TAVR is the lack of data suggesting its feasibility in low-risk patients. TAVR is currently approved for extremely high-risk patients with severe AS who are inoperable. There is data supporting the device’s use in the intermediate risk patient population. Finally, there is not much clinical information on the durability of these valves beyond 5 years of implant. This is, partly, owing to the fact that TAVR is a comparatively new procedure and most of the implantations are made in patients who are either in their 80s or 90s. Larger, more rigorous clinical trials like Partner 3 are currently underway to gather evidence for the long-term durability of valves.

Likewise, TAVR too is associated with almost all the risk factors associated with surgical replacement of aortic valves, including stroke, bleeding complications, infections or even death.

Studies have estimated that approximately 4% of patients experience a stroke within 30 days of a TAVR procedure. Leaders in the field are now trying to bring in adjunctive offerings to minimize the risks and improve TAVR patient outcomes. Claret Medical’s neurovascular brain-protection system Sentinel is an example.

The need for a permanent pacemaker after TAVR is another major issue the interventionists are trying to tide over. Irregular heartbeats due to conduction abnormalities are higher in patients undergoing percutaneous valve replacement than in surgery.

“The usual and the biggest concern that we have with most TAVR patients is whether they will be needing a pacemaker or not,” comments Dr T J Collins.

Permanent pacemaker implantation comes with short and long-term risks.