Interventional cardiology

Caution urged over extending TAVI to lower risk patients


New research suggesting that transcatheter aortic valve implantation could be extended to lower-risk patients with aortic stenosis should be treated with caution because of the absence of long-term data, an expert says.

While recommending the procedure for lower risk patients is already gaining traction overseas, Associate Professor Ravinay Bhindi, interventional cardiologist at Sydney’s Royal North Shore Hospital said the roll out of TAVI in Australia has been ‘guarded’.

“Whether that’s a good or bad thing is up for debate,” he told the limbic in an interview.

“TAVI has a very strong indication for people at high risk for an operation and has a moderate or reasonable indication for those who are intermediate risk for an operation… but we haven’t got the data at present to say that TAVI valves perform as well as surgical valves over 10-15 years, which is the average life of a bio prosthetic valve,” he said.

Dr Bhindi was referring to a recent meta-analysis in The BMJ involving 3179 patients, most of who were aged over 80 years, that found TAVI was associated with better outcomes than SAVR in terms of mortality, stroke, acute kidney injury and bleeding over a median follow-up of two years.

However, TAVI was associated with 18 more instances per 1000 patients of moderate to severe symptoms of heart failure than SAVR, the permanent insertion of 134 more pacemakers per 1000 patients and seven more aortic valve reinterventions over the short term.

According to Professor Bhindi, there are a number of other concerns about overextending the procedure to patients who are well suited for SAVR including aortic paravalvular regurgitation, high rates of pacer dependence particularly with younger patients, and native valve calcifications.

“There are now strategies and techniques that minimise these issues but these are still significant issues,” he noted.

“If you’re going to drop risk then you want to have a valve that will not have much paravavular regurgitation, that doesn’t have a high pace maker rate and that you know is at least as durable as the surgical equivalent.”

But he also acknowledged that selecting patients for either TAVI or SAVR based on surgical risk scores is problematic. While indications used in those risk scores are reasonable, he said they are not supported by evidence-based clinical trials.

“The entirety of risk is relative, someone could be low risk but they could be frail and you don’t score points for frailty on the surgical risk score,” he added.

“Ultimately a heart team is central to any discussion relating to TAVI and the heart team has to evaluate a myriad of factors in this process,” he told the limbic.

The procedure is limited in Australia because it does not have a MBS reimbursement code attached to it. The relatively small numbers of procedure that are performed are funded either by state governments or by individual hospital budgets, Professor Bhindi said.

He estimates that the Royal North Shore Hospital performs around 70 procedures each year.

In a meeting held in May this year the Medical Services Advisory Committee (MSAC) recommended the government support public funding for TAVI in patients determined to be at high risk for surgical aortic valve replacement or to be non-operable.

“The selection of a patient for a MBS-funded TAVI procedure must have been determined through an accredited TAVI multi disciplinary heart team (MDHT) … and assessment of cognitive function and frailty must included as part of any MBS item descriptor,” it said in its meeting notes.

It has also imposed a mandatory requirement for a national TAVI registry that will allow yearly patient outcome analysis.

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