Author + information
- Louis Simard, BSc,
- Jean Perron, MD,
- Mylène Shen, MSc,
- Lionel Tastet, MSc,
- Siamak Mohammadi, MD,
- Marine Clisson, BSc,
- Anthony Poulin, MD and
- Marie-Annick Clavel, DVM, PhD∗ ()
- ↵∗Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec Heart and Lung Institute, 2725, Chemin Sainte-Foy, #A-2047, Québec, QC G1V 4G5, Canada
Mechanical valves require anticoagulation therapy, and biosprotheses have a relatively short lifetime, especially in young adult patients (1). The Ross procedure may overcome these issues without any anticoagulation needed and allow for possible longer graft integrity. However, studies have pointed out high rates of reoperation (2,3). We thus aimed to identify determinants of echocardiographic degeneration of both autografts and homografts in a young adult population.
Among adult patients who underwent a Ross procedure, 263 with stenosis or insufficiency of native aortic valves were included. Clinical echocardiographic follow-up consisted of annual echocardiography during the first 3 years, every 2 years from the 4th to the 15th years, and yearly again thereafter. Follow-up was complete in all patients who underwent a mean of 1.01 ± 0.21 echocardiographies per year. The systolic blood pressure (SBP) and systolic pulmonary arterial pressure (SPAP), and systemic arterial compliance (SAC) were measured from the discharge visit to the last visit before graft degeneration criteria were met or to the last follow-up visit in patients without valve degeneration. These variables were used as time-dependent variables in the multivariable Cox models. Valvular insufficiencies were graded on a scale from 0 to 4, based on a multiparameter assessment as recommended by echocardiographic societies (4). Based on serial echocardiography examinations, we defined autograft and homograft degeneration as an increase in mean transvalvular gradients (MGs) >10 mm Hg and/or an increase of >1 insufficiency grade (>1/4) compared with pre-discharge echocardiographic examination. The time to degeneration was calculated as the time between the surgery and the time of the first observation of echocardiographic degeneration.
On average, patients were 41 ± 11 years of age, and 58% were men. The comorbidity rate was low, with 6% of patients having diabetes and 22% of patients having hypertension; 82% of patients had a bicuspid aortic valve. Predominant indication for surgery was isolated aortic stenosis (69%). Two Ross techniques were used: 84% of patients had root replacement with aortic root strengthening techniques; and 16% of patients had inclusion. Hemodynamic results were excellent in both autografts (MG: 4.8 ± 2.6 mm Hg at discharge and 5.6 ± 5.5 mm Hg at 15 years; p = 0.12) and homografts (4.0 ± 3.0 mm Hg and 8.2 ± 6.3 mm Hg; p < 0.001). More than mild insufficiency at 15 years was observed in 17 (20%) autografts and 14 (16.7%) homografts.
During a median follow-up time of 15 years (range 1 to 25 years), 38 (14%) patients underwent a second valve operation with either an autograft (n = 31; 12%) or a homograft (n = 21; 8%). Based on echocardiographic assessment, 83 (32%) autografts and 108 (41%) homografts degenerated. Interestingly, 93% of autografts and 84% of homografts reached degeneration by insufficiency. Both autograft and homograft degeneration (as time-dependent variables) were strong predictors for reoperation (hazard ratio [HR]: 153.63; 95% confidence interval [CI]: 41.13 to 573.86; p < 0.0001, and HR: 23.28; 95% CI: 7.03 to 77.13; p < 0.0001, respectively).
The degeneration rates of 10- and 20-year homografts were 24% and 61%, respectively. In Cox regression analysis adjusted for sex, age (HR: 0.98; 95% CI: 0.96 to 1.00; p = 0.04), dyslipidemia (HR: 1.47; 95% CI: 1.01 to 2.64; p = 0.05), mild pulmonary insufficiency at discharge (HR: 8.65; 95% CI: 2.53 to 29.64; p = 0.001), homograft size (HR: 1.12; 95% CI: 1.01 to 1.27; p = 0.03), and SPAP (as a time-dependent variable: HR: 1.15; 95% CI: 1.08 to 1.27 per 5 mm Hg increase; p < 0.001) were independently associated with faster homograft degeneration (Figure 1A).
The 10- and 20-year degeneration rates of the autografts were 12% and 56%, respectively. After adjustment for age, sex, and Ross technique, SBP (HR: 1.03; 95% CI: 1.02 to 1.05 per 10 mm Hg increase; p = 0.03) and SAC (HR: 1.15; 95% CI: 1.06 to 1.28; p = 0.001) (as time-dependent variables), ascending aorta replacement (HR: 7.51; 95% CI: 2.73 to 20.64; p = 0.0005), and mild aortic insufficiency at discharge (HR: 10.88; 95% CI: 1.29 to 91.44; p = 0.03) were associated with faster autograft degeneration (Figure 1B). Antihypertensive medication was not associated with less autograft degeneration, probably due to the high systolic blood pressure in several treated patients. Patients operated for pure aortic insufficiency showed a strong trend towards weaker evolution of the autograft (HR: 1.70; 95% CI: 0.97 to 2.98; p = 0.06).
The year of the surgery (accounting for changes in surgical techniques and medical therapies) was significantly associated with worse graft evolution (p = 0.001) in both models; however, it did not change the results. Considering reoperations and deaths in competitive-risks regression models also gave similar results.
In this series of patients who underwent a Ross operation, an increase in both systemic and pulmonary arterial pressures were found to be independent risk factors for autograft and homograft degeneration, respectively. These results suggested that aggressive blood pressure control should be initiated post-operatively and prolonged throughout the life of the patient to reduce the risk of potential reoperations. We hypothesized that the mechanism through which the degeneration occurs was linked to the previously demonstrated autograft dilation. The association between ascending aorta prosthesis and fast autograft degeneration could be related to an active process through which Dacron prostheses could alter the arterial tension−compliance relationship or be a passive marker of structural collagen fiber impairment. Further studies will be required to evaluate these hypotheses. Nonetheless, Ross procedure patients showed excellent and highly encouraging results with both grafts even after >20 years of follow-up. With increasing knowledge regarding the evolution of autografts and homografts, we hope to better target patients who will benefit the most from the procedure and to improve post-operative management of patients.
- 2017 American College of Cardiology Foundation
- Nishimura R.A.,
- Otto C.M.,
- Bonow R.O.,
- et al.
- David T.E.