The decreasing risk of reoperative aortic valve replacement: Implications for valve choice and transcatheter therapy

Mechanical or biological prosthesis for aortic valve replacement in patients aged 45 to 74 years

OBJECTIVE

The selection of valve prostheses for patients undergoing surgical aortic valve replacement remains controversial. In this study, we compared the long-term outcomes of patients undergoing aortic valve replacement with biological or mechanical aortic valve prostheses.

METHODS

We evaluated late results among 5762 patients aged 45 to 74 years who underwent biological or mechanical aortic valve replacement with or without concomitant coronary artery bypass from 1989 to 2019 at 4 medical centers. The Cox proportional hazards model was used to compare late survival; the age-dependent effect of prosthesis type on long-term survival was evaluated by an interaction term between age and prosthesis type. Incidences of stroke, major bleeding, and reoperation on the aortic valve after the index procedure were compared between prosthesis groups.

RESULTS

Overall, 61% (n = 3508) of patients received a bioprosthesis. The 30-day mortality rate was 1.7% (n = 58) in the bioprosthesis group and 1.5% (n = 34) in the mechanical group (P = .75). During a mean follow-up of 9.0 years, the adjusted risk of mortality was higher in the bioprosthesis group (hazard ratio, 1.30, P < .001). The long-term survival benefit associated with mechanical prosthesis persisted until 70 years of age. Bioprosthesis (vs mechanical prosthesis) was associated with a similar risk of stroke (P = .20), lower risk of major bleeding (P < .001), and higher risk of reoperation (P < .001).

CONCLUSIONS

Compared with bioprostheses, mechanical aortic valves are associated with a lower adjusted risk of long-term mortality in patients aged 70 years or less. Patients aged less than 70 years undergoing surgical aortic valve replacement should be informed of the potential survival benefit of mechanical valve substitutes.

Mechanical Valves: Past, Present, and Future-A Review

The mechanical valve was first invented in the 1950s, and since then, a wide variety of prostheses have been developed. Although mechanical valves have outstanding durability, their use necessitates life-long treatment with anticoagulants, which increases the risk of bleeding and thromboembolic events. The current guidelines recommend a mechanical prosthetic valve in patients under 50-60 years; however, for patients aged 50-70 years, the data are conflicting and there is not a clear-cut recommendation. In recent decades, progress has been made in several areas. First, the On-X mechanical valve was introduced; this valve has a lower anticoagulant requirement in the aortic position. Second, a potential alternative to vitamin K-antagonist treatment, rivaroxaban, has shown encouraging results in small-scale trials and is currently being tested in a large randomized clinical trial. Lastly, an innovative mechanical valve that eliminates the need for anticoagulant therapy is under development. We attempted to review the current literature on the subject with special emphasis on the role of mechanical valves in the current era and discuss alternatives and future innovations.

Impact of explanted valve type on aortic valve reoperations: nationwide UK experience

OBJECTIVES

This nationwide retrospective cohort study assessed the impact of the explanted valve type on reoperative outcomes in aortic valve surgery within the UK over a 23-year period.

METHODS

Data were sourced from the National Institute for Cardiovascular Outcomes Research (NICOR) database. All patients undergoing first-time isolated reoperative aortic valve replacement between 1996 and 2019 in the UK were included. Concomitant procedures, homograft implantation or aortic root enlargement were excluded. Propensity score matching was utilized to compare outcomes and risk factors for in-hospital mortality was evaluated through multivariable logistic regression. Final model selection was conducted using Akaike Information Criterion through bootstrapping. The primary end point was in-hospital mortality, and secondary end points included postoperative morbidities.

RESULTS

Out of 2371 patients, 24.9% had mechanical and 75% had bioprosthetic valves implanted during the primary procedure. Propensity matched groups of 324 patients each, were compared. In-hospital mortality for mechanical and bioprosthetic valve explants was 7.1% and 5.9%, respectively (P = 0.632). On multivariable logistic regression analysis, valve type was not a risk factor for mortality [odds ratio (OR) 0.62, 95% confidence interval (CI) 0.37-1.05; P = 0.1]. Age (OR 1.03, 95% CI 1.01-1.05; P < 0.05), left ventricular ejection fraction (OR 1.62, 95% CI 1.08-2.42; P < 0.05), creatinine ≥ 200 mg/dl (OR 2.21, 95% CI 1.17-4.04; P < 0.05) and endocarditis (OR 2.66, 95% CI 1.71-4.14; P < 0.05) emerged as risk factors for mortality.

CONCLUSIONS

The type of valve initially implanted (mechanical or bioprosthetic) did not determine mortality. Instead, age, left ventricular ejection fraction, renal impairment and endocarditis were significant risk factors for in-hospital mortality.

Degenerated Transcatheter Aortic Valve Replacement: Investigation and Management Options

With the expansion of transcatheter aortic valve replacement (TAVR) to younger and lower-surgical-risk patients, many younger and less comorbid patients will be treated with TAVR and are expected to have a life expectancy that will exceed the durability of their transcatheter heart valve. Consequently, the number of patients requiring reintervention will undoubtedly increase in the near future. Redo-TAVR and TAVR explantation followed by surgical aortic valve replacement are the different therapeutic options in the event of bioprosthetic valve failure and the need for reintervention. Patients often anticipate being able to benefit from a redo-TAVR in the event of bioprosthetic valve failure after TAVR, despite the lack of long-term data and the risk of unfavourable anatomy. Our understanding of the feasibility of redo-TAVR is constantly improving thanks to bench test studies and growing worldwide experience. However, much remains unknown. In clinical practice, one of the heart team's objectives is to anticipate the need to reaccess the coronary arteries and implant a second or even a third valve when life expectancy may exceed the durability of the transcatheter heart valve. In this review, we address key definitions in the diagnosis of structural valve deterioration and bioprosthetic valve failure, as well as patient selection and procedural planning for redo-TAVR to reduce periprocedural risk, optimise hemodynamic performance, and maintain coronary access. We describe the bench testing and literature in the redo-TAVR and TAVR explantation fields.

Risk Factors and Outcomes of Reoperative Surgical Aortic Valve Replacement in the United Kingdom

BACKGROUND

Mortality after reoperative aortic valve surgery continues to decline but remains high compared with primary isolated replacement. We sought to examine temporal trends, morbidity, and mortality among patients undergoing isolated first-time reoperative aortic valve surgery.

METHODS

The study included all patients undergoing reoperative aortic valve surgery in the United Kingdom between January 2007 and March 2019. Patients undergoing isolated reoperative aortic valve replacement (AVR) were compared with a propensity matched cohort of patients undergoing isolated primary AVR. Outcomes measured included inhospital mortality, neurologic dysfunction, postoperative dialysis, deep sternal wound infections, and hospital length of stay.

RESULTS

During the study period, 40,858 primary isolated AVRs and 3015 first-time isolated reoperative AVRs were carried out in the United Kingdom. In the propensity matched reoperative group, median age of participants was 69.8 years (60.8-76.2) with median duration between the initial surgery and the reoperation being 7.69 years. Overall mortality was 3.1% (94) for reoperative AVR compared with 1.9% (56) for primary AVR. Mortality of both primary and reoperative AVR declined during the study period. Reoperation, age, New York Heart Association class, and chronic kidney disease were independently associated with early mortality.

CONCLUSIONS

Reoperative isolated AVR can be performed with acceptable inhospital mortality and provides a benchmark against which alternative strategies should be compared.

Seven-year outcomes following aortic valve replacement with a novel tissue bioprosthesis

OBJECTIVE

As bioprosthetic aortic valve replacement (AVR) extends to younger cohorts, tissue durability is of paramount importance. We report 7-year outcomes from an AVR bioprosthesis utilizing novel tissue.

METHODS

This was an international investigational device exemption trial for novel AVR with annual follow-up and a subset re-consented at 5 years for extended 10-year follow-up. Safety end points and echocardiographic measurements were adjudicated by an independent clinical events committee and by a dedicated core laboratory, respectively.

RESULTS

Between January 2013 and March 2016, 689 patients underwent AVR with the study valve. Mean age was 66.9 ± 11.6 years, Society of Thoracic Surgeons risk score was 2.0% ± 1.8%, and 74.3% of patients were New York Heart Association functional class II and III. Five-year follow-up was completed by 512 patients, and 225 re-consented for extended follow-up. Follow-up duration was 5.3 ± 2.2 years (3665.6 patient-years), and 194 and 195 patients completed 6- and 7-year follow-ups, respectively. One-, 5-, and 7-year freedom from all-cause mortality was 97.7%, 89.4%, and 85.4%, respectively. Freedom from structural valve deterioration at 7 years was 99.3%. At 7 years, effective orifice area and mean gradients were 1.82 ± 0.57 cm2 (n = 153), and 9.4 ± 4.5 mm Hg (n = 157), respectively. At 7 years, predominantly none (96.8% [152 out of 157]) or trivial/trace (2.5% [4 out of 157]) paravalvular regurgitation and none (84.7% [133 out of 157]) or trivial/trace (11.5% [18 out of 157]) transvalvular regurgitation were observed.

CONCLUSIONS

We report the longest surgical AVR follow-up with novel tissue in an investigational device exemption trial utilizing an independent clinical events committee and an echocardiography core laboratory. This tissue demonstrates excellent outcomes through 7 years and is the benchmark for future surgical and transcatheter prostheses.