Discussion
The purpose of the paper is to guide the introduction of TAVI in regional centres by demonstrating the safe introduction at our centre. The results above and analysis below is an early indication of good efficacy and safe practice.
The PARTNER Trials demonstrated rates of Major vascular complication around 11% and 3.8% risk of stroke in TAVI patients. For accreditation a centre must demonstrate Major vascular complications less than or equal to 5 % and CVA/TIA rate less than or equal to 8%. One would expect based on these numbers to observe between one to two patients suffering a Major Vascular Complications and one episode of CVA/TIA in a cohort of 19 patients. All-cause mortality at 30 days for the comparable cohort in the in the PARTNER Trial was 6.5%, which would equate to one patient in a 19-patient cohort. The absence of these adverse outcomes in this study is likely due to the small sample size as well as careful patient selection. Given this is a pilot program it is subject to its own form of patient selection bias, in the respect that a developing program and newly accredited practitioners understandably would be more discerning and cautious in their patient selection compared. Small sample size and selection bias aside, these rates observed in this early program are reassuring that the procedure is being performed safely and comparably to other centres nationally and internationally.
Similarly the echocardiographic outcome data presented in tables 3 and 4, show promising efficacy in restoring physiological valvular gradients and function. The PARTNER trial showed rates of 12.2% for moderate to severe paravalvular leak at 30 days, while in our cohort on 10% of patients developed moderate paravalvular leak, and there were 0 cases of severe leak. (3)
If these trends continue, the department will meet ongoing ACOR accreditation requirements. Unfortunately, due to Corona Virus Disease -19 (COVID-19) the program was interrupted, hence the small sample size recorded in this paper. To-date with the re-instated program post COVID-19 precautions the department has performed 45 TAVIs, with trends noted as with the first 19 patients.
As the institution has developed, there has been a change in the care provided to patients as the program becomes more streamlined. At initiation all patients were admitted to ICU following the procedure, as the familiarity with the procedure increased, particularly towards the end of 2019 patients were increasingly admitted to CCU. All transfemoral, subclavian and anterior thoracotomy TAVIs are routinely admitted to CCU. Those who receive a hemi-sternotomy are admitted to ICU routinely. Overtime the post-procedural length of stay has been shortening. At initiation post operative stay varied considerably between 2-12 days, now patients are routinely staying between one to two days post TAVI. Soon, TAVI may become a day procedure at our centre.
The average number of procedures performed in a single session is also increasing with time. At initiation the team were only able to facilitate two patients per session, but now are routinely performing three in a single session. As patient referrals increase with the developing service this number is also set to increase with time.
Despite the unique demographics of the region, only one patient identified as Aboriginal in this cohort, which is a drastic under-representation. It is postulated to be the result of two factors, the average age of the cohort was approximately 80 years, while the Average life expectancy of ASTI people in regional Australia is between 65-75 years. Additionally, in regional and rural Australia, there is considerable epidemiological difference in the valvular pathology encountered in the ASTI and non-ASTI population, were it is common for ASTI people to present younger with other valve pathology such as infective endocarditis or rheumatic heart disease.(8) This speaks to the health inequality across Australia and particularly between the Indigenous and non-Indigenous Australians. Exemplifying why decentralisation of TAVI and introduction of a program to regional/remote Australia is an important step forward in cardiac and public health.
While the program is running well at the present time, the drive for improvement into the future is strong. The department moving forward are trailing new delivery systems for more ergonomic and effective deployment. This may further improve rates of paravalvular leak. Drafts of a standardized anti-coagulant and anti-platelet guideline post TAVI are being written with the recent publishing of the POPULAR Trial.(9) The department are actively upskilling other practitioners to increase the number of TAVI competent proceduralist. Concurrently the existing proceduralists are seeking training and accreditation with a different valve prosthesis to cater to a wider spectrum of patients, as valve sizing does limit the current scope of practice. A referral pathway is being developed and disseminated to the wider referral basin. Ideally, in the future the development of a Streamlined TAVI clinic may also occur.