Transcatheter Aortic Valve Implantation for Degenerated Surgical Aortic Bioprosthesis: A Systematic Review.

Background: Transcatheter aortic valve in valve (Aviv) replacement has been shown to be an effective therapeutic option in patients with failed aortic bioprosthetic valves. This review intended to evaluate contemporary 1-year outcomes of Aviv in recent studies.
Methods: A systematic review on outcomes of Aviv was performed using the best available evidence from studies obtained using a MEDLINE, Cochrane database, and SCOPUS search. Endpoints of interest were survival, coronary artery obstruction, prosthesis-patient mismatch (PPM), stroke, pacemaker implantation, and structural valve deterioration.
Results: A total of 3339 patients from 23 studies were included. Mean age was 68-80 years, 20%-50% were female, and Society of Thoracic Surgeons score ranged from 5.7 to 31.1. Thirty-day all-cause mortality ranged from 2% to 8%, and 1-year all-cause mortality ranged from 8% to 33%. Coronary artery obstruction risk after Aviv ranged from 0.6% to 4%. One-year stroke ranged from 2% to 8%. Moderate-severe PPM occurred in 11%-58%, and pacemaker rate at 1 year ranged from 5% to 12%.
Conclusion: Transcatheter aortic ViV has emerged as an effective therapeutic option to treat patients with failed bioprostheses. The acceptable complication rate and favorable 1-year outcomes make Aviv an appropriate alternative to redo surgical aortic valve replacement. Copyright:

INTRODUCTION

Surgical aortic valve replacement (SAVR) using tissue bioprosthetic valves remains a widely used treatment option for patients with severe aortic valve disease. Given the risk of thromboembolic and bleeding risk associated with mechanical aortic valves, there has been a shift towards increased use of bioprosthetic valves.[12] As a result, many of these patients outlive their valve durability and have surgical bioprosthetic valve degeneration. Reoperation for surgical bioprosthetic degeneration is associated with morbidity and mortality.[3] Transcatheter aortic valve-in-valve replacement (Aviv) emerged as a less invasive therapeutic option to treat patients with a failed surgical bioprosthesis. Aviv witnessed a significant evolution in tools and techniques to overcome the challenges associated with this procedure. There was also the rapid expansion of Aviv use in different types of surgical bioprosthetic valves such as stentless valves and homografts. This systematic review is an overview of recent advances and outcomes of Aviv, along with best practice recommendations.

METHODS

Literature search

Electronic searches were performed using Ovid Medline, In-Process and Nonindexed Citations and Ovid Medline Daily, Ovid Medline Daily Update, EBM Reviews-Cochrane Central Register of Controlled Trials, EBM Reviews-Cochrane Database of Systematic Reviews, Embase, SCOPUS, and PubMed from January 1, 2000 to November 24, 2020. To maximize the capture of all pertinent studies, we used the terms “bioprosthesis,” “heart valve prosthesis,” “bioprostheses,” “degenerated,” “aortic valve replacement,” “transcatheter aortic valve replacement (TAVR),” “transcatheter aortic valve implantation (TAVI)”, “Aviv,” “VIV”, “TAVI” and “TAVR.” Quality of evidence was graded using the Grading of Recommendations Assessment, Development, and Evaluation approach.[4] The reporting of this systematic review was in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.[5]

Eligibility criteria

Full manuscripts in English with human subjects were included, while abstracts, case reports, review articles, and editorials were excluded. To report outcomes, studies deemed eligible for the current systematic review included those that had data for patients with the severe aortic bioprosthetic disease who were treated by TAVR and had at least 50 patients with at least 1-year follow-up. Initial screening was done by two independent investigators (A.E., M.A.) using titles, abstracts, and full manuscripts of relevant studies. The most up-to-date studies were included if duplicate studies or those with accumulating a number of patients or lengthened follow-up time were found.

Primary variables of interest were short- and long-term mortality, coronary artery obstruction, prosthesis-patient mismatch (PPM), stroke, pacemaker risk, and prosthetic valve durability.

RESULTS

Quantity of evidence

Our initial search generated 467 total references. After screening the initial search and exclusion of duplication, abstracts, irrelevant articles, and review articles, we identified 23 full-text articles that were eligible for our systematic review, totaling 3339 patients [Figure 1]. There were 5 large main registries, (VIV International Data [VIVID]), PARTNER-2 (Placement of Aortic Transcatheter Valve) trial VIV substudy, CoreValve expanded use study, (Society of Thoracic Surgeons/American College of Cardiology [STS/ACC]) Transcatheter Valve Therapy Registry, VIVA (Registry) along with several other smaller studies.[678910111213141516171819202122]

Figure 1

PRISMA flow chart for literature search

Quality of evidence

All studies included in this systematic review were observational multicenter registry studies with reported patient demographics, procedural outcomes, 30 days, and 1-year follow-up outcomes.

Baseline demographics

Baseline demographics between the studies were comparable. A summary of the baseline demographics is shown in Table 1. Mean age ranged between 68 and 80 years. Female gender was reported in 20%–50% of patients. STS score ranged from 5.7 to 31.1. The mode of failure was stenosis in 23%–68% of patients, regurgitation in 11%–67% of patients, and 10%–30% had mixed aortic valve prosthetic disease. Failed bioprosthetic valve type differed among studies. Failed valve type was stented valve in 77%–100% of patients, stentless in 6%–91% of patients, and homograft in 1%–9%.[678910111213141516171819202122]

TABLE 1

Patients’ clinical characteristics and surgical valves characteristics

Registry	References	Study Period	ViV (n)	Age	Women (%)	STS-PROM Score	Logistic Euro SCORE	NYHA Class III-IV	Stenosis	Regurgitation	Mixed	Stented Valve (%)	Stentless Valve (%)	Homograft (%)	<20 mm ID Valve (%)
Global ViV	Dvir et al. (5)	2012	202	77.7±10.4	47	31.1±16.4	31.1±16.4	94	42	34	24	77	23	NA	26
VIVID	Dvir et al. (5) Pibarot et al. (23) Ribeiro et al. (21) Simonato et al. (24)	2014	459	77.6±9.8	44	10 (6.2-16.1)	29 (19.1-42.3)	92	39	30	30	80	20	NA	27
CoreValve U.S. Expanded Use Study	Deeb et al (4)	2017	233	76.7±10.8	37	9.0±6.7	23.7±16.5	87	56	22	22	82	11	7	14
Partner – 2 VIV	Webb et al. (10) Webb et al. (26)	2017 2019	365	78.9±10.2	36	9.1±4.7	12.3±9.8	90	55	24	21	92	6	NA	47
STS/ACC	Tuzcu et al (9)	2018	1150	79 (74-85)	39	6.9 (4.5-10.8)	NA	85	61	12	25	NA	NA	NA	34
SWISS-TAVI	Ferrari et al (12)	2018	157	78±9.1	40	6.4±5	28.48±15.3	75	68	32	NA	89	10	1	NA
Multicenter- Long-term Outcomes	De Freitas Campos Gulmaraes et al. (11)	2018	116	76±11	35	8.0±5.1	NA	77	41	36	22	76	24	0	24
VIVA Post-Market	Tchetche et al. (8)	2019	202	79.9±7.2	52	6.6±5.1	25.0±14.3	69	56	23	21	93	7	0	41
Multicenter- Stentless	Miller et al. (15)	2019	66	68.1 (56.9-79.4)	20	5.7±6.1	NA	NA	23	67	10	0	91	9	NA
Multicenter- AccurateNeo	Holzamer et al. (13)	2019	85	77±8	46	6.8±6.9	11.4±7.9	NA	56	44 (regurgitation-mixed)	44 (regurgitation-mixed)	NA	NA	NA	41
3 Centers	Raschipichler et al. (17)	2020	74	77.0 (69.2-86.0)	50	6.80 (3.74-12.3)	NA	92	59	11	30	NA	NA	NA	23
Single Center-Mitroflow	Pascual et al. (16)	2020	65	80.4±5.9	49	6.39±5.62	24.0±15.1	82	39	34	28	100 Mitroflow	0	0	28
Redo-TAVR International	Landes et al. (14)	2020	165	79.72 (74-84)	39	6.5 (4.8-9.6)	NA	78	36	35	29	NA	NA	NA	NA

Numerical variables were presented with mean±SD or median (IQR). IQR: Interquartile range, SD: Standard deviation, NA: Not available, ID: Internal diameter, STS: Society of Thoracic Surgeons, NYHA: New York Heart Association, VIV: Valve in valve, VIVA: Aortic VIV, VIVID: VIV International Data, ACC: American College of Cardiology, TAV: Transcatheter aortic valve, TAVI: TAV implantation, TAVR: TAV replacement

Assessment of primary endpoints

Procedural outcomes are summarized in Table 2. Transfemoral access was the predominant access route which ranged 67%–100% of study patients. In the different studies, Aviv was performed using several commercial transcatheter heart valves (THV), including balloon-expandable valve, several types of self-expanding valves, and mechanically expandable valves.[78919202123] The largest experience was derived from the use of Sapien XT/Sapien 3 (Edwards Lifesciences, Irvine, CA) and Corevalve/Evolut (Medtronic, Minneapolis, MN).[78919202123]

TABLE 2

Procedural characteristics and outcomes

Registry	References	Publication Year	ViV (n)	Edwards Balloon Expandable (%)	Medtronic Self Expandable (&)	Others (%)	TF (%)	Alternative (%)	All-cause Mortality (%)	Stroke (%)	Coronary Obstruction (%)	Pacemaker (%)	≥20 mmHg Gradient (%)	Moderate-Severe PPM (%)
Global ViV	Dvir et al. (5)	2012	202	39	61	0	67	33	30-d: 8 1-7:14	30-d: 2	30-d: 3.5	30-d: 7	28	NA
VIVID	Dvir et al. (5) Pibarot et al. (23) Ribeiro et al. (21) Simonato et al. (24)	2014	459	54	46	0	59	41	30-2:8 1-7:17	30-d: 2	30-d: 2	30-d: 5	27	32
CoreValve U.S. Expanded Use Study	Deeb et al (4)	2017	233	0	100	0	NA	NA	30-d: 2 1-Y: 15	30-d: 3 1-Y: 8	30-d: 1	30-d: 8 1-Y: 11	NA	11
Partner – 2 VIV	Webb et al. (10) Webb et al. (26)	2017 2019	365	100	0	0	75	25	30-d: 3 1-Y: 12 3-Y: 33	30-d: 3 1-Y: 4.5	30-d: 1	30-d: 2	34	58
STS/ACC	Tuzcu et al (9)	2018	1150	44	56	0	88	12	30-d: 3 1-Y: 12	30-d: 2 1-Y: 3	Inhospital: 0.6	Inhospital: 3	NA	NA
SWISS-TAVI	Ferrari et al (12)	2018	157	32	61	7	90	10	30-d: 2 1-Y: 7	30-d: 0.6 1-Y: 2	NA	30-d: 3 1-Y: 5	NA	NA
Multicenter- Long-term Outcomes	De Freitas Campos Gulmaraes et al. (11)	2018	116	48	52	0	71	29	30-d: 7 3-Y: 26	30-d: 2	30-d: 1	30-d: 5	NA	35
VIVA Post-Market	Tchetche et al. (8)	2019	202	0	100	0	97	3	30-d: 2.5 1-Y: 9	30-d: 3 1-Y: 6	30-d: 2 1-y: 2.5	30-d: 8 1-Y: 12	NA	NA
Multicenter- Stentless	Miller et al. (15)	2019	66	74	26	0	100	0	30-d: 3 1-Y: 10	30-d: 3	30-d: 9	30-d: 8	NA	NA
Multicenter- AccurateNeo	Holzamer et al. (13)	2019	84	0	0	100 (Accurate Neo)	100	0	30-d: 5 1-Y: 8	30-d: 1	30-d: 1	30-d: 1	NA	43
3 Centers	Raschipichler et al. (17)	2020	74	77	20	3	91	9	30-d: 5 1-Y: 13	30-d: 2	30-d: 0	30-d: 7	33	NA
Single Center- Mitroflow	Pascual et al. (16)	2020	65	0	100	0	94	6	30-d: 3	30-d: 2	NA	30-d: 5	NA	32
Redo-TAVR International	Landes et al. (14)	2020	624	NA	NA	NA	88	12	30-d: 4 1-Y: 10	30-d: 0.6	30-d: 4	30-d: 8	22	NA

30-d: 30 days, 1-y: 1-year, 3-y: 3-year, Retro-OS: Retrospective observational study, Pro-OS: Prospective observational study, NA: Not available, PPM: Prosthesis patient mismatch, TF: Transfemoral, VIV: Valve in valve, VIVA: Aortic VIV, VIVID: VIV International Data, STS: Society of Thoracic Surgeons, ACC: American College of Cardiology, TAV: Transcatheter aortic valve, TAVI: TAV implantation, TAVR: TAV replacement

The median 30-day all-cause mortality was 4% (Interquartile range [IQR] 2.75%–6%)6789101112131416192021 [Figure 2]. The majority of patients experienced improvement of symptoms and were in New York Heart Association Class I-II (median 93%, IQR 89%–94%) within 30-day.[9141921] In the VIVID registry, the median duration of hospital stay was 8 days and 92.6% improved to York Heart Association functional Class I-II, with no difference between self-expandable and balloon-expandable valves.[9] 1-year all-cause mortality ranged between 7% and 17%, and the median 1-year survival in the studies was 88% (IQR 86%–91%) [Table 2].[79192021] The emergent procedure, dialysis, nontransfemoral access, anemia, thrombocytopenia, and high postprocedural mean gradient (≥20 mmHg) were associated with increased 1-year mortality were independently associated with decreased 1-year survival.[20]

Figure 2

Summary of 30-day and 1-year clinical adverse events using boxplot. The boxplot demonstrates the median and interquartile range of the percentage of clinical adverse events reported in published registries

The 30-day stroke risk ranged from 0.6% to 3%, whereas the 1-year stroke risk ranged from 2% to 8%. Coronary obstruction risk ranged from 0.6% to 9%, and 30-day pacemaker risk ranged from 1% to 8%. Moderate-severe PPM was present in 11%–58% of patients, and the postprocedural mean gradient was higher than 20 mmHg in 22%–34% [Figure 3]. There was variation in the outcomes depending on the type of surgical valve treated, as summarized in Table 2.[678910111213141516171819202122]

Figure 3

Summary of patients who developed postprocedural high mean aortic gradient or severe prosthesis-patient mismatch using boxplot. The boxplot demonstrates the median and interquartile range of the percentage of high mean aortic gradient as well as moderate and severe prosthesis-patient mismatch reported in published registries. Abbreviations: prosthesis-patient mismatch, patient prosthesis mismatch

Assessment of durability

Few studies examined the rate of structural valve degeneration (SVD) in the patients who underwent Aviv implantation. The PARTNER 2 Aviv sub-study evaluated the rates of SVD over 3 years period.[22]

Moderate SVD (moderate stenosis or transvalvular regurgitation) occurred in 2 out of 160 patients (1.3%), and severe SVD (severe stenosis or transvalvular regurgitation) occurred in 2 out of 160 patients (1.3%) at 3 years.[22] Moreover, there were 5 (1.9%) repeat aortic valve replacements over the same duration of follow-up.[22] In another study looking at subclinical and clinical SVD, the authors discovered 18 out of 99 (18.2%) of SVD cases (3% clinical and 15.2 subclinical) that occurred 1–4 years from the indexed procedure.[6]

Aviv versus redo surgical aortic valve replacement

Smaller studies comparing Aviv to redo SAVR revealed similar 30-day all-cause mortality.[2425] In one study, the 30-day all-cause mortality in both groups was 7.4% and 7.5%, respectively, with longer intensive care unit and hospital stay in the redo SAVR group.[24] In another retrospective study comparing these groups, 30-day mortality was 4.5% for Aviv and 4.1% for redo SAVR (P = 0.87), with a longer hospital stay for the redo SAVR group.[25] The overall 1-year survival between transcatheter Viv and redo SAVR was similar. Woitek F et al. demonstrated an 8.8% rate of 1-year mortality in patients treated with Aviv versus 9.9% in patients treated with redo SAVR (P = 0.84).[25] Stankowski T et al. reported comparable 1-year survival between Aviv and redo SAVR (85.2% vs. 85.0%, P = 0.287).[24]

Two analyses compared stroke rate in Aviv versus redo SAVR. The first was a propensity-matched analysis showing a similar stroke rate (10.3% vs. 5%; P = 0.336),[24] and the other was not propensity-matched and also showed a similar stroke rate (5.4% vs. 8.1%; P = 0.39).[25] Overall rates of pacemaker implantation after Aviv procedure were similar to redo SAVR when both treatment strategies were compared to each other.[2425]

DISCUSSION

The findings of this systematic review show that (1) transcatheter Aviv treatment for failed aortic bioprosthetic valves is safe and effective with reasonable 30 days and 1-year survival, (2) Rate of early transcatheter SVD is low, (3) Procedural outcomes vary depending on the type of failed bioprosthetic valve, (4) Survival outcomes of Aviv were comparable to redo SAVR and (5) elevated transaortic gradients and PPM was prevalent in the study cohorts. This data supports the use of Aviv as an alternative to redo SAVR.

Early experience and lessons learned

Aviv for failed bioprosthesis evolved with time. Early on, Aviv was performed in a high-risk population (median STS score of 31.1), in predominantly failed stented valves, and using Medtronic self-expanding valve in 61% of cases and 39% with Edwards balloon-expandable valves. Alternative access was prevalent and used in 33%–41% of cases. One-year all-cause mortality was high 14%–17%, 30-day stroke risk was 2%, coronary artery obstruction risk was 3.5%, 30-day pacemaker risk was 7%, and residual gradient ≥20 mmHg was 28%.[8] Several lessons were learned from this early experience, which led to improvements in both technique and technology. Moreover, as the experience was gained, Aviv was expanded to treat a variety of failed bioprosthetic valve types such as the stentless and transcatheter aortic valves.

Choice of transcatheter heart valves

As the expertise grew with Aviv, data on outcomes of different types of THV's used emerged.

Access route

Alternative access decreased with time, and most of Aviv was done via transfemoral route, irrespective of the THV type.[678910111213141516171819202122]

Mortality data

There was no significant difference in 30 days and 1-year mortality according to THV type, including self-expandable and balloon-expandable THV's, Portico and CoreValve, older generation Sapien XT and Sapien S3.[6789101113192022]

Coronary artery obstruction

There was no association between the transcatheter valve type and the rate of coronary artery occlusion.[1729]

Stroke

Stroke rate was the similar for self-expanding compared to balloon expandable valves (0.9 vs. 2.4; P = 0.22),[9] Corevalve compared to Portico (1.9 vs. 0.9; P = 0.11)[28] and SAPIEN XT compared to the next generation SAPIEN S3 (2% vs. 0.5%; P = 0.184).[23] Stroke rate did not appear to change temporally[678910111213141516171819202122] [Table 2].

Pacemaker risk

CoreValve/Evolut and low implantation depth were the two most important procedural factors for increased rates of pacemaker implantation.[923] In an early publication from the VIVID registry, the prevalence of pacemaker implantation after Aviv using self-expandable was 12.2% compared to 4.9% after using balloon-expandable valves (P = 0.005).[9]

Moreover, the reported rates of pacemaker implantation (8%–11%) were higher in self-expandable ViV registries such as CoreValve U. S. Expanded use and VIVA registries[719] compared to the 2% rate reported in Partner-2 Viv substudy.[21] The rates of pacemaker implantation in the ACCURATE neo ViV observational study were very low as well at 1%.[11]

Prosthesis-patient mismatch

Use of balloon-expandable and intra-annular TAVR prostheses, particularly if implanted in preexisting small surgical bioprostheses,[915212829] stenosis as a mode of failure,[789] presence of preexisting PPM,[715] and low TAVR prosthesis implantation depth,[111823] was associated with higher rates of postprocedural transvalvular gradient and PPM.

Data on the prognostic significance of postprocedural PPM was variable. Earlier analyses from VIVID and PARTNER-2 demonstrated an association between PPM, small preexisting surgical valves, and high postprocedural mean aortic gradient with worse intermediate-term clinical outcomes, including mortality.[91521] However, subsequent analyses with longer-term follow-up at 3–7 years did not demonstrate a significant difference in outcomes when patients grouped into high versus. low gradient and postprocedural PPM versus. no PPM.[62130]

The above findings from various studies can be used to guide the choice of THV type and technique to provide the most favorable outcomes. For example, the use of self-expanding supra-annular valves in small failed surgical valves via transfemoral route and implanted high enough to lower pacemaker risk and lower the gradient may offer the most optimal outcomes.

Impact of failed surgical valve

Different studies showed variability in the outcomes of transcatheter Aviv amongst the different types of failed bioprosthetic valves. Coronary artery obstruction risk was associated with the type of failed bioprosthetic valve. The mechanism of coronary artery obstruction was showed be due to leaflet displacement into the ostium of the coronary artery.[17] Unsurprisingly, the predictors of coronary artery obstruction were prior use of stentless or stented with externally mounted leaflets bioprostheses as well as a virtual transcatheter to coronary artery distance obtained by preprocedural computed tomography scan of <4 mm.[17] The latter is obtained by placing a virtual transcatheter valve in the aortic position parallel to the axis of the failed bioprosthetic valve, and a distance from the virtual valve to both coronary artery Ostia is measured. In a study looking at the outcomes of TAVR in 66 failed stentless bioprosthetic aortic valves, the rate of acute coronary obstruction was extremely high at 9.1%.[13] Moreover, in the VIVA registry, the rate of coronary artery obstruction was 2%, all of which occurred using balloon-expandable transcatheter valves inside Mitroflow surgical valves with externally mounted leaflets.[19]

An early publication from the Global VIV registry reported a high coronary artery obstruction rate at 3.5% with transcatheter Aviv procedures.[8]

In subsequent publications after the recognition of this complication from VIVID, the rate of coronary artery obstruction decreased to 1%–2% in the CoreValve U. S Expanded use, PARTNER-2 Viv sub-study, VIVA registry, and STS/ACC TVT registries.[79192021]

As for PPM, the size and status of the failed bioprosthetic valve did influence the rate of PPM. Small pre-existing surgical valves (≤20 mm Internal Diameter)[67891011162021], stenosis as a mode of failure,[789] presence of pre-existing PPM[715] were associated with post-procedural PPM. The type of failed bioprosthetic valve did not appear to influence the rate of stroke and pacemaker implantation.[678910111213141516171819202122]

Therefore, the type and size of failed bioprosthetic valve have an associated impact on PPM and coronary artery obstruction risk predominantly, which is important to factor into procedural planning and considerations.[78919202123]

Contemporary techniques in planning and executing transcatheter aviv

Given the findings of the studies, predominant drivers of outcomes that pose a challenge for Aviv include 1-Access route, 2-Coronary artery occlusion risk, 3-Stroke risk, and 4-PPM. Recent advances in the field of Aviv included the development of techniques and technologies that would help improve outcomes and mitigate risks associated with the above procedural considerations. Strategies to decrease the risk of these complications are summarized in Figure 4.

Figure 4

Suggested algorithm in planning and executing transcatheter Valve in valve procedures using contemporary techniques

Access

Transfemoral access remains to be the predominant and safest route of access in Aviv.[26273132] The introduction of angioplasty using lithotripsy balloon in iliofemoral calcific disease facilitated the transfemoral route in patients who were otherwise not considered to be transfemoral candidates in the past.[32] Moreover, more alternative access sites emerged and evolved as options that avoid disrupting the thoracic cage, as in the case of the transapical route. Such accesses include percutaneous transaxillary, transcarotid and transcaval accesses.[263132]

Coronary artery occlusion risk

Coronary artery protection techniques evolved to actively mitigate the risk of coronary artery occlusion in patients deemed high risk for that ( Virtual Transcatheter Valve to Coronary Distance VTC <4 mm). Two main techniques were commonly used recently and continue to evolve. The first technique is chimney stenting, which involves placing a coronary guidewire and stent during Aviv.[33] If coronary artery obstruction is detected, the stent is then retracted to extend from the coronary ostium and parallel to the THV frame and deployed, creating a channel for coronary perfusion. In the International Chimney Registry, patients who had upfront did better than those who had this technique as a bailout. However, long-term outcomes of stents deployed using this technique remain unknown.[33] Another procedural advancement is intentional bioprosthetic leaflet laceration using electrosurgical techniques, commonly known as the BASILICA technique.[34] In the BASILICA registry, this technique was shown to be successful in 86.9% of cases, with a reported 4.7% coronary obstruction despite the laceration. Mortality was 3.4% at 30 days, and stroke risk was 2.8%. Survival was 83.9% at 1 year. Longer-term data is also lacking.[34]

Gradient

Besides high implantation and use of THV prosthesis with supra-annular leaflets, surgical valve ring cracking with high-pressure noncompliant balloon has emerged as an alternative method to reduce postprocedural gradient and reduce the rate of PPM.[35] However, the safety and efficacy of this procedure need to be rigorously studied in large prospective studies before it is widely used.

Embolic protection devices have emerged as an option to lower the risk of stroke during Aviv. This is done by either capturing embolic debris through baskets placed in the right innominate and left carotid artery (Sentinel device) or by deflecting emboli by covering all the arch of the aorta branches (TriGuard).[36] However, early clinical trial data have failed to show a reduction of clinical stroke rate and is a matter of continued investigation.[37]

LIMITATIONS

The main limitation of this systematic review is that most of the patients included in this analysis were studied in a retrospective fashion which could introduce selection bias. In addition, long-term clinical and echocardiographic data are limited. Therefore, the long-term effects of Aviv are not well understood. Furthermore, these registries included mostly high surgical risk patients. Therefore, the role of Aviv in low to intermediate-risk patients is not known at this time but is being evaluated in a prospective study (PARTNER 3 intermediate-risk Aviv Registry, NCT 03003299). This registry will provide insights regarding the role of Aviv in low to intermediate-risk patients and the long-term effects, as well include a 10-year follow-up. Last, an important limitation is the underrepresentation of female patients in these registries, ranging between 20% and 50% of patients. Further studies including more female patients are needed.

CONCLUSION

Aviv has emerged as a safe and feasible therapeutic option in patients with a failed bioprosthetic valve. Careful planning and execution using contemporary techniques have helped mitigate risks such as coronary artery obstruction, PPM, and stroke. Contemporary data suggest that Aviv is a reasonable alternative for high surgical risk patients. The role of Aviv in intermediate-risk patients is being evaluated in a prospective clinical trial. Further studies with long-term follow-up are needed to understand the long-term effects of Aviv.

Financial support and sponsorship

Nil.

Conflicts of interest

Dr. Guerrero has received research grant support from Abbott Vascular and Edwards Lifesciences.