Sign In

Forgot your password?

Password Reset

Beginners Guide to TAVI

Beginners Guide to TAVI

Dr Marwa Daghem, Cardiology Trainee ST7, Liverpool Heart and Chest Hospital



PART 1- Pre-procedure assessment and planning

Two decades on from the first transcatheter aortic valve implantation (TAVI), procedural rates are growing exponentially, with over 6000 procedures performed annually across the United Kingdom(1). Contemporary trials such as PARTNER 3(2), Evolut Low Risk(3)and UK TAVI trial (4)have demonstrated superiority, or at least non-inferiority, to surgery in low-risk patients. As such recommendations for TAVI in patients with severe symptomatic aortic stenosis have expanded to include all patients over 75 years of age, as well as patients < 75 years of age who are at high or intermediate risk for surgery(5). Given the growing demands on the service, there needs to be an accompanying growth in training and service provision. Even cardiologists without budding structural aspirations will need some working knowledge of the procedure to facilitate appropriate patient selection and allow for streamlining of existing services.


Patient Selection

Optimal patient selection is the key to a successful TAVI procedure, with the multidisciplinary team playing an instrumental role in this process. Appropriate selection is based on both the patient’s clinical and anatomical criteria, with a balanced consideration of survival and expected quality of life versus the risk of complications.

From a clinical perspective, symptoms must be evaluated and correlated with the degree of Aortic stenosis. These patients are often elderly with multiple co-morbidities, and it can be difficult to allocate symptoms legitimately to the valvular heart disease; precise evaluation of the severity of aortic stenosis is therefore crucial for patient management and risk stratification.

It is important to have a clear understanding of patients’ pre-existing comorbidities such as prior strokes, renal impairment, chronic obstructive airways disease – which confer a high procedural risk and may necessitate pre- or intra-procedural risk modification, such as the use of embolic protection devices to reduce stroke risk or pre-procedural hydration and contrast minimisation to reduce the risk of kidney injury. Patients with a large number of co-morbidities may have a poor prognosis and may not benefit from intervention.

The presence of any previous cardiac history should be noted, the concomitant presence of coronary artery disease may necessitate prior PCI – such is the case in 13% of TAVI cases in the UK(1). In patients with a previous valve prosthesis, it is important to note the model and size of the valve. Redo surgical aortic valve replacement has conventionally been the treatment of choice for failed surgical valves, however valve-in valve (ViV) transcatheter aortic valve implantation (TAVI) is fast emerging as a viable, less invasive alternative with the potential for improved short-term morbidity and mortality compared to surgery(6,7). With increasing numbers of young patients with surgical bio-prostheses, we can expect an increase in valve-in-valve interventions in the coming years. These are often higher-risk TAVI procedures requiring careful anatomical assessment and technical expertise to minimise the risk of patient-prosthesis mismatch and coronary obstruction.

Complicating the care of severe aortic stenosis patients is the high incidence of frailty(8) which confers a higher risk of death and poor mobility – above and beyond the risk attributed to age and comorbidities(9). As such patients with a high frailty score are less likely to benefit from this procedure.


Pre-procedure planning and anatomical assessment

All patients being considered for TAVI need a full diagnostic work up, including evaluation of aortic valve morphology, root anatomy, arterial vasculature, and calcium distribution to determine the valve type and size and vascular access.

The development of advanced atrioventricular conduction abnormalities is one of the main risks of TAVI, owing to the anatomical proximity of the aortic valve to the atrioventricular node/His-Purkinje system.  The presence of a right bundle branch block (RBBB) on electrocardiogram (ECG) is associated with a high pacemaker risk (10) and will often necessitate keeping a temporary pacing wire (TPW) in post-procedure, with anticipated longer post procedural monitoring and potential device necessity.

Transthoracic echocardiography is the first line tool in the pre-workup assessment for aortic stenosis patients and provides detailed anatomy of the aortic valve (bicuspid/tricuspid valve) as well as providing haemodynamic information relating to the severity of stenosis – namely the velocity, gradients and functional aortic valve area derived using the continuity equation. Evaluation of left ventricular systolic function also helps inform procedural risk; the presence of EF<50% constitutes a negative prognostic marker(11).

In cases of discordant grading of aortic stenosis severity, computed tomography (CT) calcium scoring should be performed (thresholds for severe aortic stenosis are 2000 for males, 1,250 for females (12)). Meanwhile, contrast enhanced CT imaging plays a pivotal role in procedural planning for TAVI, providing a wealth of anatomical information:

  1. Vascular access: vascular complications are independently associated with morbidity and mortality after TAVI(13). Analysis of iliofemoral vessel size, calcification and tortuosity helps determine suitability for transfemoral access. If transfemoral TAVI is unsuitable, the second access of choice is usually trans left subclavian/axillary artery. A comprehensive assessment of co-existing vascular pathologies such as aneurysms, dissections and occlusions is also essential for access planning and may help guide the need for vascular team involvement.
  2. Valve and root morphology- namely presence of bicuspid/tricuspid valve. Assessment of any aortopathy is relevant, especially in patients with bicuspid aortic valves.
  3. Aortic annular and root dimensions: measurements of the aortic annulus are usually performed in systole in the annular plane(14). If the diameter is borderline between two valve sizes, consider the smaller valve size in the presence of severe annular calcification, narrow root, low coronary ostia, bulky leaflets, or mitral annular calcification(15).
  4. Coronary ostial heights: low ostial heights (<12mm) from annulus to sinus of Valsalva connote a high risk of coronary occlusion(14). This should be assessed in the context of overall root dimension and anticipated valve type/size, as this varies considerably between different valves.
  5. Annular/sub-annular and LVOT calcification: the presence of calcification in the LVOT and aortic valve is associated with increased risk of paravalvular regurgitation(16). The risk of annular rupture increases with the degree of calcification of the upper part of the LVOT. Furthermore, severe calcification of the sub-annular device landing zone confers a higher risk of atrioventricular conduction block(17) and subsequent need for a permanent pacemaker.
  6. CT derived co-planar fluoroscopic angle prediction can help guide implantation angle.


Potential procedure complications:

Technological advances and growing procedural experience have yielded a reduction in major complication rates for TAVI.  Nonetheless, this is not a risk-free procedure carrying an over-all risk of major complications of 5-7%. It is important to have a frank and open discussion with patients about the main periprocedural complications which include:

  1. There is a 1.8% of in-hospital mortality compared to 4-5% ten years ago(18).
  2. Stroke risk is low at less that 2%(1). Periprocedural embolic strokes tend to occur in the first 48 hrs and account for half of TAVI related strokes. Trials are ongoing to assess whether cerebral protection during the procedure will be helpful in mitigating stroke risk in these patients, including the UK-wide BHF PROTECT study (NCT02895737), the largest ever RCT in TAVI globally.
  3. There is a 2-3% risk of major vascular complications(18). The risk has been significantly reduced by decreasing the profile of the sheaths and catheters used to deliver the valves.
  4. Coronary occlusion is a rare (incidence < 1%) but life-threatening complication of TAVI that occurs more frequently with balloon-expandable valves, and in those patients  with a previous surgical bioprosthesis (19).
  5. Based on registry data the risk of moderate-severe paravalvular leak (PVL) is 3-4%(18). This maybe secondary to improper sizing, too low or too high valve placement, incomplete expansion, or bulky annular calcification. The incidence of PVL is much lower with newer generation valves that have external ceiling skirts covering the periprosthetic space (2).
  6. There is a risk of high degree Atrioventricular block. UK data shows a 9% rate of pacemaker implantation post TAVI(1), with higher rates seen with Medtronic valves compared to Edwards valves.


In conclusion:

Transcatheter aortic valve implantation (TAVI) is a well-established treatment option for patients with severe symptomatic aortic stenosis, whose procedural efficacy and safety have been continuously improving.  One of the key points for success with TAVI is careful preprocedural planning including a comprehensive clinical assessment, the use of multi-modality imaging to ensure appropriate patient selection, allow valve sizing and foresee and mitigate against possible procedure-related complications.



  1. Ludman PF. UK National Audit Transcatheter Aortic Valve Implantation 1st April 2019 to 31st March 2020. NICOR/BCIS; 2020.
  2. Mack MJ., Leon MB., Thourani VH., et al. Transcatheter Aortic-Valve Replacement with a Balloon-Expandable Valve in Low-Risk Patients. New Engl J Med 2019;380(18):1695–705. Doi: 10.1056/nejmoa1814052.
  3. Popma JJ., Deeb GM., Yakubov SJ., et al. Transcatheter Aortic-Valve Replacement with a Self-Expanding Valve in Low-Risk Patients. New Engl J Med 2019;380(18):1706–15. Doi: 10.1056/nejmoa1816885.
  4. Investigators TUTT., Fairbairn T., Kemp I., et al. Effect of Transcatheter Aortic Valve Implantation vs Surgical Aortic Valve Replacement on All-Cause Mortality in Patients With Aortic Stenosis. Jama 2022;327(19):1875–87. Doi: 10.1001/jama.2022.5776.
  5. Vahanian A., Beyersdorf F., Praz F., et al. 2021 ESC/EACTS Guidelines for the management of valvular heart disease. Eurointervention 2022;17(14):e1126–96. Doi: 10.4244/eij-e-21-00009.
  6. Tam DY., Dharma C., Rocha RV., et al. Transcatheter ViV Versus Redo Surgical AVR for the Management of Failed Biological Prosthesis Early and Late Outcomes in a Propensity-Matched Cohort. Jacc Cardiovasc Interventions 2020;13(6):765–74. Doi: 10.1016/j.jcin.2019.10.030.
  7. Webb JG., Murdoch DJ., Alu MC., et al. 3-Year Outcomes After Valve-in-Valve Transcatheter Aortic Valve Replacement for Degenerated Bioprostheses The PARTNER 2 Registry. J Am Coll Cardiol 2019;73(21):2647–55. Doi: 10.1016/j.jacc.2019.03.483.
  8. Green P., Woglom AE., Genereux P., et al. The Impact of Frailty Status on Survival After Transcatheter Aortic Valve Replacement in Older Adults With Severe Aortic Stenosis A Single-Center Experience. Jacc Cardiovasc Interventions 2012;5(9):974–81. Doi: 10.1016/j.jcin.2012.06.011.
  9. Stortecky S., Schoenenberger AW., Moser A., et al. Evaluation of Multidimensional Geriatric Assessment as a Predictor of Mortality and Cardiovascular Events After Transcatheter Aortic Valve Implantation. Jacc Cardiovasc Interventions 2012;5(5):489–96. Doi: 10.1016/j.jcin.2012.02.012.
  10. Siontis GCM., Jüni P., Pilgrim T., et al. Predictors of Permanent Pacemaker Implantation in Patients With Severe Aortic Stenosis Undergoing TAVR A Meta-Analysis. J Am Coll Cardiol 2014;64(2):129–40. Doi: 10.1016/j.jacc.2014.04.033.
  11. Elmariah S., Palacios IF., McAndrew T., et al. Outcomes of Transcatheter and Surgical Aortic Valve Replacement in High-Risk Patients With Aortic Stenosis and Left Ventricular Dysfunction: Results From the Placement of Aortic Transcatheter Valves (PARTNER) Trial (Cohort A). Circulation Cardiovasc Interventions 2013;6(6):604–14. Doi: 10.1161/circinterventions.113.000650.
  12. Aggarwal SR., Clavel M-A., Messika-Zeitoun D., et al. Sex Differences in Aortic Valve Calcification Measured by Multidetector Computed Tomography in Aortic Stenosis. Circulation Cardiovasc Imaging 2018;6(1):40–7. Doi: 10.1161/circimaging.112.980052.
  13. Steinvil A., Leshem-Rubinow E., Halkin A., et al. Vascular Complications After Transcatheter Aortic Valve Implantation and Their Association With Mortality Reevaluated by the Valve Academic Research Consortium Definitions. Am J Cardiol 2015;115(1):100–6. Doi: 10.1016/j.amjcard.2014.09.047.
  14. Blanke P., Weir-McCall JR., Achenbach S., et al. Computed Tomography Imaging in the Context of Transcatheter Aortic Valve Implantation (TAVI)/Transcatheter Aortic Valve Replacement (TAVR). Jacc Cardiovasc Imaging 2019;12(1):1–24. Doi: 10.1016/j.jcmg.2018.12.003.
  15. Zamorano JL., Gonçalves A., Lang R. Imaging to select and guide transcatheter aortic valve implantation. Eur Heart J 2014;35(24):1578–87. Doi: 10.1093/eurheartj/eht569.
  16. Okuno T., Asami M., Heg D., et al. Impact of Left Ventricular Outflow Tract Calcification on Procedural Outcomes After Transcatheter Aortic Valve Replacement. Jacc Cardiovasc Interventions 2020;13(15):1789–99. Doi: 10.1016/j.jcin.2020.04.015.
  17. Katchi F., Bhatt D., Markowitz SM., et al. Impact of Aortomitral Continuity Calcification on Need for Permanent Pacemaker After Transcatheter Aortic Valve Replacement. Circulation Cardiovasc Imaging 2019;12(12):e009570. Doi: 10.1161/circimaging.119.009570.
  18. Ludman PF. UK TAVI registry. Heart 2019;105(Suppl 2):s2. Doi: 10.1136/heartjnl-2018-313510.
  19. Ribeiro HB., Webb JG., Makkar RR., et al. Predictive Factors, Management, and Clinical Outcomes of Coronary Obstruction Following Transcatheter Aortic Valve Implantation Insights From a Large Multicenter Registry. J Am Coll Cardiol 2013;62(17):1552–62. Doi: 10.1016/j.jacc.2013.07.040.