A look at recent improvements in the durability of tissue valves

Biomechanics of Transcatheter Aortic Valve Implant

Transcatheter aortic valve implantation (TAVI) has grown exponentially within the cardiology and cardiac surgical spheres. It has now become a routine approach for treating aortic stenosis. Several concerns have been raised about TAVI in comparison to conventional surgical aortic valve replacement (SAVR). The primary concerns regard the longevity of the valves. Several factors have been identified which may predict poor outcomes following TAVI. To this end, the lesser-used finite element analysis (FEA) was used to quantify the properties of calcifications which affect TAVI valves. This method can also be used in conjunction with other integrated software to ascertain the functionality of these valves. Other imaging modalities such as multi-detector row computed tomography (MDCT) are now widely available, which can accurately size aortic valve annuli. This may help reduce the incidence of paravalvular leaks and regurgitation which may necessitate further intervention. Structural valve degeneration (SVD) remains a key factor, with varying results from current studies. The true incidence of SVD in TAVI compared to SAVR remains unclear due to the lack of long-term data. It is now widely accepted that both are part of the armamentarium and are not mutually exclusive. Decision making in terms of appropriate interventions should be undertaken via shared decision making involving heart teams.

Percutaneous versus Surgical Intervention for Severe Aortic Valve Stenosis: A Systematic Review

Aortic stenosis is a disease that is increasing in prevalence and manifests as decreased cardiac output, which if left untreated can result in heart failure and ultimately death. It is primarily a disease of the elderly who often have multiple comorbidities. The advent of transcatheter aortic valve therapies has changed the way we treat these conditions. However, long-term results of these therapies remain uncertain. Recently, there has been an increasing number of studies examining the role of both surgical aortic valve replacement and transcatheter aortic valve replacement. We therefore performed a systematic review using Ovid MEDLINE, Ovid Embase, and the Cochrane Library. Two investigators searched papers published between January 1, 2007, and to date using the following terms: "aortic valve stenosis," "aortic valve operation," and "transcatheter aortic valve therapy." Both strategies in aortic stenosis treatment highlighted specific indications alongside the pitfalls such as structural valve degeneration and valve thrombosis which have a bearing on clinical outcomes. We propose some recommendations to help clinicians in the decision-making process as technological improvements make both surgical and transcatheter therapies viable options for patients with aortic stenosis. Finally, we assess the role of finite element analysis in patient selection for aortic valve replacement. THVT and AVR-S are both useful tools in the armamentarium against aortic stenosis. The decision between the two treatment strategies should be best guided by a strong robust evidence base, ideally with a long-term follow-up. This is best performed by the heart team with the patient as the center of the discussion.

Long-term Follow-up After Transcatheter Aortic Valve Replacement

Background

Transcatheter aortic valve replacement (TAVR) has become the standard of care in the majority of patients with symptomatic severe aortic stenosis. Data on long-term mortality and durability of transcatheter heart valves (THVs) beyond 5 years are limited. Our study aimed to assess elderly and high-risk patients’ long-term outcomes treated with TAVR in a prospective single-centre registry focusing on the durability of THVs.

Methods

We included 795 patients with severe calcific aortic stenosis treated by transfemoral TAVR between 2006 and 2011. Echocardiography was performed at baseline; discharge; 1 year; and afterward, annually, until the longest available follow-up. Mortality rates were estimated for 1, 5, 6, 7, and 8 years. The rates of structural valve deterioration (SVD) and bioprosthetic valve failure (BVF) were assessed in accordance with consensus definitions. Outcome measures were adjudicated according to Valve Academic Research Consortium-2 (VARC-2).

Results

Median (interquartile range) follow-up time was 1345 (316; 2015) days. One-year, 5-year, 6-year, 7-year, and 8-year overall mortality was 25.4%, 59.0%, 64.6%, 67.9%, and 69.2%, respectively. At 8 years, no significant differences in mortality were found comparing self-expanding vs balloon-expandable valves (69.5% vs 68.0%, P = 0.709) and postdilatation (PD) vs no-PD (69.4% vs 69.2%, P = 0.363). SVD was detected in 26 patients (3.3%), and 19 (2.4%) of the 795 patients had evidence of BVF during follow-up.

Conclusions

Our study demonstrates good long-term results for high-risk patients who were alive up to 8 years after TAVR.

Selection of prosthetic aortic valves in the United States among elderly Medicare patients from 2006 to 2015

BACKGROUND

Both biological and mechanical prosthetic valves are treatment choices for aortic valve replacement. We aimed to characterize the selection of prosthetic aortic valves among elderly Medicare patients.

METHODS

This was a retrospective analysis of patients aged 65 years or older who underwent aortic valve replacement alone or in combination with other procedures in the 2006-2015 Medicare databases. Patients were continuously enrolled in Medicare Part A and B. We characterized the trends and regional variation of the selection of prosthetic valves. Multivariable logistic regression was used to evaluate the determinants that influenced the selection of prosthetic valves.

RESULTS

During the study period, there were 272,921 Medicare patients aged 65 years or older who underwent aortic valve replacement and met the inclusion and exclusion criteria. The selection of mechanical aortic valves decreased from 32.0% in 2006 to 24.3% in 2015 (P < .01). In comparison with 18.5% from northeastern states, 34.6% of patients from southern states selected mechanical valves (P < .01). Major determinants of the selection of prosthetic valves include age, gender, region, hospital characteristics, and physician experience. Patients being older, male, living in the northeast region, operated on in a high-volume hospital, and by more experienced physicians were more likely to receive biological valves.

CONCLUSIONS

A 24.1% decrease in the selection of mechanical aortic valves was observed among elderly Medicare patients from 2006 to 2015. A dramatic regional difference was observed in the choice of prosthetic valves across the nation.

Standardized Definition of Structural Valve Degeneration for Surgical and Transcatheter Bioprosthetic Aortic Valves

Bioprostheses are prone to structural valve degeneration, resulting in limited long-term durability. A significant challenge when comparing the durability of different types of bioprostheses is the lack of a standardized terminology for the definition of a degenerated valve. This issue becomes especially important when we try to compare the degeneration rate of surgically inserted and transcatheter bioprosthetic valves. This document, by the VIVID (Valve-in-Valve International Data), proposes practical and standardized definitions of valve degeneration and provides recommendations for the timing of clinical and imaging follow-up assessments accordingly. Its goal is to improve the quality of research and clinical care for patients with deteriorated bioprostheses by providing objective and strict criteria that can be utilized in future clinical trials. We hope that the adoption of these criteria by both the cardiological and surgical communities will lead to improved comparability and interpretation of durability analyses.

Iranian homograft heart valves: assessment of durability and late outcome

Durability and the rate of complications of homograft heart valves, adjusted for patient-related contributors and surgical techniques, rely mainly on the quality of allografts which in turn are mirrored in the donor characteristics and most importantly recovery and processing procedures. Aimed to assess the quality, a study was conducted to figure out the durability and late outcome following homograft replacement with valved conduits procured by the Iranian Tissue Bank. Retrospectively, the pre-implantation, perioperative and follow-up data of 400 non-consecutive recipients of cryopreserved heart valves (222 pulmonary and 178 aortic) from 2006 to 2015 were collected and analyzed in terms of variables reflecting late outcome including adverse events and durability. In the context of durability, the event of interest was defined as the need for homograft replacement and homograft-related death. The mean follow-up time (SD) of study entrants (male/female ratio, 1.4) was 49.8 (36.3) months. Median age at the time of implantation was 11 years. Total 10-years mortality was 21 % (84/400), including 66.7 % early (30-days mortality: 56/84) and 33.3 % late (28/84). Overall late complication rate was 2 %. Median survival time was 120 months (95 % CI 83.3-156.6). The pulmonary valves appeared to be more durable (P value <0.001) and survival probabilities in small sized grafts were lower (P value 0.008). One-, five-, and ten-year graft survival was 82, 76 and 73 %, respectively. The evidences suggest that the homografts function satisfactory with low rate of late complications; nevertheless, more emphasis should be given to make long-term durability comparable.

The future of transcatheter aortic valve implantation

Since the introduction of transcatheter aortic valve implantation (TAVI) into clinical practice, the treatment of aortic stenosis has changed dramatically. In the past, medical therapy with or without balloon aortic valvuloplasty was the only option for inoperable patients. More recently, TAVI has become the treatment of choice for these patients and the preferred alternative for high-risk operable patients. Surgical aortic valve replacement (SAVR) currently remains the gold standard for patients at low or intermediate operative risk. As randomized trials have demonstrated comparable results between TAVI and SAVR in the high-risk population, there is now a clear trend towards performing TAVI even in intermediate-risk patients while awaiting the results of randomized trials in that population. Nevertheless, there are still questions regarding TAVI involving paravalvular leak (PVL), stroke, pacemaker requirements, and durability that remain to be more definitively answered before TAVI can routinely be performed in a broader, lower risk population. Improvements in patient selection, imaging, and second and third generation devices have decreased the incidence of PVLs and vascular complications that followed the earliest TAVI procedures, but the rates of perioperative stroke and permanent pacemaker implantation must still be addressed. Furthermore, the long-term durability of TAVI devices and a role for post-procedure antithrombotic management remain unanswered. Until these questions are more clearly answered, it is the Heart Team's task to determine the optimal treatment for each patient based on risk scores, frailty metrics, comorbidities, patient preference, and potential for improvement in quality of life.

Long-term results after treatment of the ascending aorta for bicuspid aortic valve patients

PURPOSE

We evaluated the long-term results of aortic valve replacement for bicuspid aortic valve patients with or without surgical treatment of the ascending aorta.

METHODS

A total of 145 bicuspid aortic valve patients had undergone aortic valve replacement since 1974 at our institution. No surgical treatment (Group-N; n = 115) was performed in the ascending aorta if the diameter was less than 40 mm. We wrapped an ascending aorta of 40-50 mm with an artificial graft (Group-W; n = 19), and performed replacement (Group-R; n = 11) if the ascending aorta measured more than 50 mm. Follow-up was completed for 144 patients (99.3 % of the cases).

RESULTS

The hospital mortality rate was 1.4 %. There were no significant differences among Groups N, W and R in the freedom from valve-related death and cardiac death at 10 years after surgery. The rates of freedom from aorta-related events in the three groups at 10 years after surgery were 98.3 % (Group-N), 100 % (Group-W) and 100 % (Group-R).

CONCLUSIONS

The long-term survival was equivalent among the three groups, and the rates of freedom from aorta-related death or events were low. Our surgical protocol for the treatment of the enlarged ascending aorta associated with BAV is appropriate.

Minimally invasive approach to calcified aortic valve replacement: Anaesthetic considerations

For symptomatic patients with severe calcified aortic valve stenosis, open heart surgery for aortic valve replacement remains the gold standard. However, elderly patients with an increased risk profile can be treated by using transcatheter approaches (transcatheter aortic valve implantation [TAVI]). The major considerations related to use of general and local anaesthesia for TAVI are discussed in this review.

Impact of Ross Operation on Outcome in Young Female Adult Patients Wanting to Have Children

BACKGROUND

The most appropriate valve substitute at aortic valve replacement (AVR) for young female adult patients wanting to have children is unclear.

METHODS AND RESULTS

Between 1992 and 2013, 12 consecutive female patients aged >18 (median, 22.5 years; range, 18-34 years) underwent Ross operation (Ross group). Between 1984 and 2013, 9 consecutive female patients aged >18 (median, 30 years; range, 22-39 years) underwent AVR with bioprosthesis (bioprosthesis group). There was 1 late mortality in the bioprosthesis group, due to prosthetic valve endocarditis (PVE). Freedom from reoperation for aortic valve at 15 years was 90.0% in the Ross group, and 57.1% in the bioprosthesis group (log-rank, P=0.098). One in the Ross group underwent reoperation for aortic regurgitation (AR), whereas 4 in the bioprosthesis group did so for aortic stenosis (AS) in 2, combined AS and AR in 1, and PVE in 1. Five patients in the Ross group and 3 in the bioprosthesis group had 7 and 4 uneventful pregnancies, respectively. AR progressed during the perinatal period in a total of 7 of 11 pregnancies. No AS was seen at discharge, after 5 years, or during pregnancy in the Ross group.

CONCLUSIONS

The long-term outcome of Ross operation for female patients wanting to have children is excellent. Although subclinical pulmonary autograft valve regurgitation during pregnancy was often observed, pulmonary autograft stenosis did not occur, therefore it would be an ideal option for patients wanting to have children.

Long-term durability of pericardial valves in the aortic position in younger patients: when does reoperation become necessary?

BACKGROUND

We sought to assess the long-term durability of pericardial valves in patients at age <65 years undergoing aortic valve replacement (AVR), and to determine the timing of redo operations due to structural valve deterioration (SVD).

METHODS

From 1986 to 2001, a total of 574 adult patients underwent AVR with pericardial valves in nine hospitals in Japan. Of these, 53 patients were at age <65 years (group Y). These patients were compared with those of age ≥ 65 (group O, n = 521).

RESULTS

The mean follow-up duration was 9.5 years in group Y and 8.1 years in group O. Freedom from reoperation due to SVD was 100% at five years, 90.8% at 10 years, and 47.2% at 15 years in group Y, and 99.3% at five years, 97.4% at 10 years, and 94.4% at 15 years in group O (log-rank test, p < 0.01). In those who required redo AVR in group Y (n = 12), the mean time from initial operation to reoperation was 12.1 years. The reoperation-free survival curve started to decline after eight years postoperation in group Y.

CONCLUSIONS

Redo AVR started to become necessary eight years after surgery in the patients who underwent AVR with pericardial valve at age <65 years. In addition, approximately half of those patients required reoperation due to SVD by 15 years postoperatively.