Introduction to the TAVI Atlas
Taken from the original PCR Valve Atlas app
Aortic stenosis (AS) is the most frequent native valve disease in Europe and the United States and thus represents an important public health problem. The management of AS is made challenging by the fact that most patients are elderly with comorbidities which renders decision making and the choice of the most appropriate treatment more difficult.
For a long time aortic valve replacement (AVR) was the only possible intervention. The evidence available today consistently shows the efficacy of TAVI in terms of improvement in valve function, reduction in mortality versus medical therapy, and improvement in quality of life up to five or six years in inoperable patients. AVR provided excellent results, both immediate and long-term; however, it also carries a high risk in many patients with comorbidities, something which led to practitioners denying surgery to a sizeable number of patients, as shown by the Euro Heart Survey.
In 2002, Alain Cribier revolutionised the field by introducing transcatheter aortic valve implantation (TAVI) as a complementary technique to surgery. Now, well over 100,000 patients have been treated, which allows a better evaluation of the results of the technique. The evidence available today consistently shows the efficacy of TAVI in terms of improvement in valve function, reduction in mortality versus medical therapy, and improvement in quality of life up to five or six years in inoperable patients. In operable but high-risk patients, the results appear to be non-inferior and even, in a recent publication, superior to surgery.
There are still complications of the technique which remain a concern: among them are the presence of paravalvular aortic regurgitation, stroke and vascular complications. These complications decrease over time with experience, better patient selection on clinical grounds and also using imaging techniques, and better care.
The technique of TAVI has improved dramatically: this is due to procedural planning using sophisticated imaging where CT now plays an increasing role besides echocardiography. Training is provided as regards the technique in general, but device-specific training is also given. Finally, the devices are constantly improving, with a lower profile, refinements in technology allowing for a significant decrease in paravalvular regurgitation as well as repositionability and retractability capacities.
The indications for the technique based on the evidence available have been proposed on both sides of the ocean, firstly by the 2012 ESC/EACTS guidelines and this year by the ACC/AHA guidelines. The two documents concur on most points. They firstly stress the crucial importance of the Heart Team in performing patient selection and also procedural performance as well as post-procedural care. This team is composed of interventional cardiologists, cardiac surgeons, general cardiologists, imaging specialists, anaesthesiologists and other specialists, when needed, such as geriatricians. The concordant opinion on both sides of the ocean is that this procedure should only be performed in hospitals with cardiac surgery on-site and experience in the management of high-risk patients with valve disease to improve safety of the procedure but more importantly to optimise patient selection and postoperative care.
TAVI is now unambiguously recommended in patients with severe symptomatic AS who are considered unsuitable for conventional surgery by the Heart Team but are likely to get improvement in their quality of life and to have sufficient life expectancy. Progress will occur by decreasing the number of patients where intervention is more futile than utile: this requires the development and assessment of risk factors such as frailty which are insufficiently used at present. In patients who are high risk for surgery, once again TAVI should be considered if it is the preferred option chosen by the Heart Team, taking into consideration the prospective advantages and disadvantages of the two techniques. The ESC/EACTS guidelines were the first to introduce the concept that evaluation of the risk should not rely on isolated thresholds of STS score or EuroSCORE but take into account all the characteristics of the patient and the Heart Team evaluation. This is now also proposed by the ACC/AHA guidelines.
At the present stage neither set of guidelines recommends performing TAVI in patients at intermediate low risk for surgery, and both encourage participating in trials. In answer to this, the PARTNER II trial has now completed enrolment and SURTAVI is currently enrolling. The incentives for performing TAVI in this patient population are the good results observed in observational studies but longer follow-up is definitely needed. In addition, further studies are necessary to explore what are currently considered as relative contraindications for TAVI, such as the management of patients with associated mitral regurgitation. In this domain we need more studies separating the management of patients with primary from those with secondary MR. Concomitant coronary disease is a challenge and here an individualised approach is needed based on the patient's clinical condition, coronary anatomy and extent of myocardium at risk. Randomised studies to answer this question are ongoing. Bicuspid valves will be more frequent if indications are expanded to lower-risk patients. Here the evidence from the literature is limited and the selection of patients should be cautious, driven strictly by clinical needs after a very careful assessment of anatomy on the size of the annulus and type of calcification. Patients with very low left ventricular ejection fraction or haemodynamic instability remain a challenge and are not included in the most recent trials.
Thus, at the present stage, the future of TAVI is very promising which emphasises the need for good educational tools.
It is likely that the current clinical atlas of transcatheter aortic valve therapy will meet our expectations since it will address the most important points of knowledge in the procedure, that is to say firstly a comprehensive description of the anatomy of the aortovalvular complex which is key for understanding the efficacy but also the limitations of the techniques. It is also key for understanding the needs and results of any imaging technique. Then, the extremely lively and up-to-date presentation of the procedure, including cases but also a description of the devices and guidance for the management of complications, will be very helpful, including the description of accessories for TAVI. The particularities of valve-in-valve treatment will be addressed with its specific aspects in terms of education for performance of the procedure. Finally, the core issue of the "Heart Team" will be practically addressed using actual examples of Heart Team recordings.
The editors, co-editors, PCRonline editorial board and other numerous contributors should be congratulated for providing the cardiology community with such a tool, which will no doubt be very helpful for the practice of all those interested in transcatheter aortic valve implantation.