Aortic replacement in the setting of bicuspid aortic valve: How big? How much?

Association of Thoracic Aortic Aneurysm Size With Long-term Patient Outcomes: The KP-TAA Study

Importance

The risk of adverse events from ascending thoracic aorta aneurysm (TAA) is poorly understood but drives clinical decision-making.

Objective

To evaluate the association of TAA size with outcomes in nonsyndromic patients in a large non-referral-based health care delivery system.

Design, Setting, and Participants

The Kaiser Permanente Thoracic Aortic Aneurysm (KP-TAA) cohort study was a retrospective cohort study at Kaiser Permanente Northern California, a fully integrated health care delivery system insuring and providing care for more than 4.5 million persons. Nonsyndromic patients from a regional TAA safety net tracking system were included. Imaging data including maximum TAA size were merged with electronic health record (EHR) and comprehensive death data to obtain demographic characteristics, comorbidities, medications, laboratory values, vital signs, and subsequent outcomes. Unadjusted rates were calculated and the association of TAA size with outcomes was evaluated in multivariable competing risk models that categorized TAA size as a baseline and time-updated variable and accounted for potential confounders. Data were analyzed from January 2018 to August 2021.

Exposures

TAA size.

Main Outcomes and Measures

Aortic dissection (AD), all-cause death, and elective aortic surgery.

Results

Of 6372 patients with TAA identified between 2000 and 2016 (mean [SD] age, 68.6 [13.0] years; 2050 female individuals [32.2%] and 4322 male individuals [67.8%]), mean (SD) initial TAA size was 4.4 (0.5) cm (828 individuals [13.0% of cohort] had initial TAA size 5.0 cm or larger and 280 [4.4%] 5.5 cm or larger). Rates of AD were low across a mean (SD) 3.7 (2.5) years of follow-up (44 individuals [0.7% of cohort]; incidence 0.22 events per 100 person-years). Larger initial aortic size was associated with higher risk of AD and all-cause death in multivariable models, with an inflection point in risk at 6.0 cm. Estimated adjusted risks of AD within 5 years were 0.3% (95% CI, 0.3-0.7), 0.6% (95% CI, 0.4-1.3), 1.5% (95% CI, 1.2-3.9), 3.6% (95% CI, 1.8-12.8), and 10.5% (95% CI, 2.7-44.3) in patients with TAA size of 4.0 to 4.4 cm, 4.5 to 4.9 cm, 5.0 to 5.4 cm, 5.5 to 5.9 cm, and 6.0 cm or larger, respectively, in time-updated models. Rates of the composite outcome of AD and all-cause death were higher than for AD alone, but a similar inflection point for increased risk was observed at 6.0 cm.

Conclusions and Relevance

In a large sociodemographically diverse cohort of patients with TAA, absolute risk of aortic dissection was low but increased with larger aortic sizes after adjustment for potential confounders and competing risks. Our data support current consensus guidelines recommending prophylactic surgery in nonsyndromic individuals with TAA at a 5.5-cm threshold.

Management of Adults With Normally Functioning Congenitally Bicuspid Aortic Valves and Dilated Ascending Aortas

We describe herein a 65-year-old woman who underwent resection of a dilated (5.1 cm) ascending aorta associated with a normally functioning congenitally bicuspid aortic valve. The patient provided the framework to discuss proper management-operative versus nonoperative-of the dilated ascending aorta associated with a normally functioning bicuspid aortic valve. Unfortunately, there is inadequate data to provide an unequivocal answer to this dilemma. Operative intervention requires that the short-term risk of the prophylactic procedure be considerably lower than the long-term risk of aortic dissection/rupture without operative intervention. Because there is no proof that operative intervention provides less morbidity and lower mortality, nonoperative management at this time seems to be the better approach.

Evolving Surgical Approaches to Bicuspid Aortic Valve Associated Aortopathy

Bicuspid aortic valve (BAV) is the most common congenital cardiac pathology which results from the fusion of two adjacent aortic valve cusps. It is associated with dilatation of the aorta, known as bicuspid valve-associated aortopathy or bicuspid aortopathy. Bicuspid aortopathy is progressive and is linked with adverse clinical events. Hence, frequent monitoring and early intervention with prophylactic surgical resection of the proximal aorta is often recommended. Over the past two decades resection strategies and surgical interventions have mainly been directed by surgeon and institution preferences. These practices have ranged from conservative to aggressive approaches based on aortic size and growth criteria. This strategy, however, may not best reflect the risks of important aortic events. A new set of guidelines was proposed for the treatment of bicuspid aortopathy. Herein, we will highlight the most recent findings pertinent to bicuspid aortopathy and its management in the context of a case presentation.

The aortic root does not dilate over time after replacement of the aortic valve and ascending aorta in patients with bicuspid or tricuspid aortic valves

OBJECTIVE

Whether the aortopathy associated with bicuspid aortic valve (BAV) disease occurs secondary to genetic or hemodynamic factors remains controversial. In this article we describe the natural history of the aortic root in patients with bicuspid versus tricuspid aortic valves (TAVs) after replacement of the aortic valve and ascending aorta.

METHODS

From 1990 to 2010, 406 patients (269 BAV, 137 TAV) underwent aortic valve and ascending aorta replacement at a single institution. Patients with aortic dissection, endocarditis, previous aortic surgery, or Marfan syndrome were excluded. All available follow-up imaging was reviewed.

RESULTS

Mean imaging follow-up was 5.5 (±5.3) years. Of all patients, 66.5% had at least 1 aortic root measurement after the index operation. Baseline aortic diameter was comparable between groups. In patients with BAV, aortic root diameter increased at a clinically negligible rate over time (0.654 mm per year; 95% confidence interval, 0.291-1.016; P < .001), similar to patients with TAV (P = .92). Mean clinical follow-up was 8.1 (±5.4) years. During follow-up, 18 patients underwent reoperation, 89% for a degenerated bioprosthetic aortic valve. Only 1 patient underwent reoperation for a primary indication of aortic aneurysmal disease, 22 years after the index operation. There were no differences in cumulative incidence rates of aortic reoperation (P = .14) between patients with BAV and TAV.

CONCLUSIONS

Mid-term imaging after aortic valve and ascending aorta replacement indicates that if the aortic root is not dilated at the time of surgery, the risk of enlargement over time is minimal, negating the need for prophylactic root replacement in patients with BAV or TAV.

Evolution of Precision Medicine and Surgical Strategies for Bicuspid Aortic Valve-Associated Aortopathy

Bicuspid aortic valve (BAV) is a common congenital cardiac malformation affecting 1–2% of people. BAV results from fusion of two adjacent aortic valve cusps, and is associated with dilatation of the aorta, known as bicuspid valve associated aortopathy. Bicuspid valve aortopathy is progressive and associated with catastrophic clinical events, such as aortic dissection and rupture. Therefore, frequent monitoring and early intervention with prophylactic surgical resection of the proximal aorta is often recommended. However, the specific pattern of aortopathy is highly variable among patients, with different segments of the ascending aorta being affected. Individual patient risks are sometimes difficult to predict. Resection strategies are informed by current surgical guidelines which are primarily based on aortic size and growth criteria. These criteria may not optimally reflect the risk of important aortic events. To address these issues in the care of patients with bicuspid valve aortopathy, our translational research group has focused on validating use of novel imaging techniques to establish non-invasive hemodynamic biomarkers for risk-stratifying BAV patients. In this article, we review recent efforts, successes, and ongoing challenges in the development of more precise and individualized surgical approaches for patients with bicuspid aortic valves and associated aortic disease.

Year in review: bicuspid aortopathy

PURPOSE OF REVIEW

This article outlines the key research contribution to bicuspid aortic valve (BAV) aortopathy over the past 18 months.

RECENT FINDINGS

Investigators have further defined the current gaps in knowledge and the scope of the clinical problem of BAV aortopathy. Support for aggressive resection strategies is waning as evidence mounts to suggest that BAV is not similar to genetic connective tissue disorders with respect to aortic risks. The role of cusp fusion patterns and valve-mediated hemodynamics in disease progression is a major area of discovery. Molecular and cellular mechanisms remain elusive and contradictory.

SUMMARY

BAV aortopathy is a major public health problem that remains poorly understood. New insights on valve-mediated hemodynamics using novel imaging modalities may lead to more individualized resection strategies and improved clinical guidelines.