Article

Transcatheter aortic valve replacement/implantation has revolutionized the landscape of treatment for aortic stenosis

Aortic stenosis (AS) is an age-related degenerative disease with a high mortality if not treated. India is currently overburdened with AS, both rheumatic and non-rheumatic. The number of deaths due to calcific aortic valve disease have increased gradually over the last decade in India.1

 

A single center study by Manjunath et al. in India showed isolated aortic stenosis as the third most common (7.3%) valve lesion in an adult population, degenerative calcific as the most common cause (65%) followed by bicuspid aortic valve (33.9%). Rheumatic heart disease contributes to 1.1%.2

 

Although surgical aortic valve replacement (SAVR) is a class I recommendation for severe symptomatic AS according to American College of Cardiology/American Heart Association (ACC/AHA) guidelines, nearly one third patients are unable to undergo SAVR because of comorbidities, frailty, left ventricular dysfunction, and advanced age.1

 

The development of transcatheter aortic valve replacement/implantation (TAVR/TAVI) has emerged as a lifeline for patients considered to be inoperable providing both improvement in symptoms and statistically significant mortality benefit.3

 

The first approval of TAVR for the indication of severe AS in prohibitive risk patients came in 2011. In 2012, the FDA approved TAVR in patients at high surgical risk. In 2015 the indication was expanded to include “valve-in-valve” procedure for failed surgical bioprosthetic valves. In 2016 the FDA approved TAVR valves for use in patients with severe AS at intermediate risk.  In 2019, the FDA further expanded the indication for TAVR valves to include low risk patients.3

 

Based on recent Indian demographics profile data and extrapolating western prevalence data to the Indian population, nearly 2.5–3 lakh patients with AS are likely to be eligible for TAVR. 

The first successful TAVR was performed in India in the year 2011 in an octogenarian lady with a previous history of coronary artery bypass graft and a porcelain aorta with severe AS that was left unoperated for 12 years and became the cause of her recurrent heart failure admissions. 1,4  Currently TAVR is being done in around 30 centers across India out of which approximately seven centers are handling the majority of the TAVR load. These procedures in India are done with both U.S. FDA approved and indigenous valves. 1

TAVI has improved outcomes for many patients with AS, including high-risk and inoperable patients.5 Early data shows that in India, TAVR is a good alternative for symptomatic severe AS for high surgical risk cases.6

 

The results of a study which analyzed data of procedural and in-hospital outcomes of TAVI in bicuspid aortic valve cases (n=70) performed at two high volume centers in India and their follow up for two years demonstrated good procedural success rates and clinical outcomes among all the patients who underwent TAVI across all risk scores. 4

Although the understanding of comorbidities and their impact on TAVI outcomes has improved, there is still a need to refine the prediction tools, and better understand the impact of TAVI on quality of life and function.5

 

It is of utmost importance to appreciate the full spectrum of potential procedural complications of TAVI and their impact on early and long-term outcomes. TAVR technique includes the need of fluoroscopy and angiography using contrast agent to aid positioning of the valve, which may lead to contrast induced nephropathy as one form or one etiology of  acute kidney injury (AKI) which is associated with increased morbidity and mortality.7

 

The knowledge of risk factors and available preventive measures can help in the appropriate selection of patient, procedure technique, and postprocedural management.8

 

Randomized control trials 9, 10 demonstrated comparable survival with either TAVR or SAVR for high-risk patients. Within the complications of each approach, AKI has been demonstrated to be less prevalent with TAVR as compared with SAVR patients as reported in recent meta-analysis of 50 studies enrolling 44,247 patients.11

 

Having abnormal baseline renal function is one of the strongest independent predictors of mortality and AKI and correlates with the AKI incidence post-TAVR. As with any interventional procedure using contrast agents, contrast-induced nephropathy is a key component parallel to other pre-disposing factors.12 The occurrence of AKI post-TAVR was associated directly with the amount of intraoperative contrast agent in a study conducted in high-risk patients who received TAVI for symptomatic aortic valve stenosis during a 3-year period. Intra-operative contrast-agent burden >99 ml (OR=2.3, p=0.038), was an independent risk factor for AKI post-TAVR. 13

 

Another study conducted in a TAVI cohort of 415 patients suggested a simple formula integrating the amount of volume of contrast media (CM) and renal function that may predict the risk of AKI after TAVI. The ratio of CM to  serum creatinine (SCr) and body weight (BW) was calculated as defining the degree of CM use.  The ratio of CM × SCr/BW >2.7 could be considered as a threshold value to decrease the risk of AKI during TAVI.14

 

Since its introduction, the technology of TAVR has undergone rapid expansion and seems to be on its way to an all-risk indication. 1 However, financial implications, non-availability of expertise, lack of awareness, lack of indigenous valves and hardware and peculiar anatomical features of Indian population remain the major challenges in India. 1,6   

During initial years of implementation of a nationwide TAVI program, it may be advisable to collate the outcomes of large volume centers performing TAVR and focus on creating TAVR centers of excellence.6 With increasingly ageing population, TAVR will likely play a critical role in the future of cardiovascular health of India. 1

 

Abbreviations:

AS: Aortic stenosis

ACC: American College of Cardiology

AHA: American Heart Association

AKI: Acute kidney injury

CM: Contrast media volume

SAVR: Surgical aortic valve replacement

TAVI: Transcatheter aortic valve implantation

TAVR: Transcatheter aortic valve replacement

 

References:

  1. Gupta P, Arora S, Qamar A, Gupta M, Seth A. Current status of transcatheter aortic valve replacement in India. Cardiovasc Diagn Ther. 2020 Feb;10(1):83-88.

  2. Manjunath CN, Srinivas P, Ravindranath KS, Dhanalakshmi C. Incidence and patterns of valvular heart disease in a tertiary care high-volume cardiac center: a single center experience. Indian Heart J. 2014 May-Jun;66(3):320-6.

  3. Mahmaljy H, Tawney A, Young M. Transcatheter Aortic Valve Replacement. 2022 May 5. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 28613729.

  4. Kumar V, Sengottuvelu G, Singh VP, Rastogi V, Seth A. Transcatheter Aortic Valve Implantation for Severe Bicuspid Aortic Stenosis - 2 Years Follow up Experience From India. Front Cardiovasc Med. 2022 Jul 28; 9:817705.

  5. Kush P Patel, Thomas Treibel, Paul Scully, Michael Fertleman, Samuel Searle, Daniel Davis, James C Moon, Michael J Mullen, Futility in Transcatheter Aortic Valve Implantation: A Search for Clarity, Interventional Cardiology 2022;17: e01.

  6. Gunasekaran S, Sivaprakasam MC, PaulPandi VK, et al. Transcatheter aortic valve replacement in India-Early experience, challenges, and outcomes from a single center. Indian Heart J. 2018 Dec;70 Suppl 3(Suppl 3): S347-S352

  7. Scherner M, Wahlers T. Acute kidney injury after transcatheter aortic valve implantation. J Thorac Dis. 2015 Sep;7(9):1527-35.

  8. Zaleska-Kociecka M, Dabrowski M, Stepinska J. Acute kidney injury after transcatheter aortic valve replacement in the elderly: outcomes and risk management. Clin Interv Aging. 2019 Jan 21;14:195-201.

  9. Smith CR, Leon MB, Mack MJ, PARTNER Trial Investigators. Transcatheter versus surgical aortic-valve replacement in high-risk patients. N Engl J Med. 2011 Jun 9;364(23):2187-98

  10. Mack MJ, Leon MB, Smith CR, et al. PARTNER 1 trial investigators. 5-year outcomes of transcatheter aortic valve replacement or surgical aortic valve replacement for high surgical risk patients with aortic stenosis (PARTNER 1): a randomised controlled trial. Lancet. 2015 Jun 20;385(9986):2477-84)

  11. Villablanca PA, Mathew V, Thourani VH, A meta-analysis and meta-regression of long-term outcomes of transcatheter versus surgical aortic valve replacement for severe aortic stenosis. Int J Cardiol. 2016 Dec 15;225:234-243.

  12. Villablanca PA, Ramakrishna H. The Renal Frontier in TAVR. J Cardiothorac Vasc Anesth. 2017 Jun;31(3):800-803

  13. Van Linden A, Kempfert J, Rastan A, et al. Risk of acute kidney injury after minimally invasive transapical aortic valve implantation in 270 patients. Eur J Cardiothorac Surg. 2011 Jun;39(6):835-42; discussion 842-3.

  14. Yamamoto M, Hayashida K, Mouillet G et al. Renal function-based contrast dosing predicts acute kidney injury following transcatheter aortic valve implantation. JACC Cardiovasc Interv. 2013 May;6(5):479-86.