Is myocardial adaptation distinct in patients with bicuspid versus tricuspid severe aortic stenosis undergoing surgical valve replacement?

Abstract Introduction Current guidelines for aortic stenosis (AS) do not distinguish between patients with bicuspid (BAV) and tricuspid aortic valve (TAV) disease, despite notable differences in their clinical profiles and possible physiopathology. Whether these differences extend to myocardial adaptation to severe aortic stenosis remains unclear. Aim To assess left ventricular adaptation in patients with severe symptomatic AS undergoing surgical aortic valve replacement (SAVR) according to the presence of BAV and TAV disease. Methods Single-center, prospective cohort study of 158 patients with severe symptomatic AS (mean age 71±8 years, 50% male; mean transaortic gradient 61±17 mmHg, indexed aortic valve area 0.4±0.1 cm²/m², LVEF 58±9%) referred for SAVR between 2019 and 2022. Patients with prior cardiomyopathy, moderate/severe aortic regurgitation, or severe non-AS valve dysfunction were excluded. Serial transthoracic echocardiography and cardiac magnetic resonance (CMR) were performed within 3 months before SAVR to assess LV remodelling and myocardial tissue characterization (T1 mapping, late gadolinium enhancement LGE, and extracellular volume- ECV). Myocardial tissue obtained during SAVR (myocardial biopsy at LV basal septum or harvested from surgical myectomy specimens) underwent collagen/fibrosis quantification with Masson’s trichrome satin at an automatic algorithm platform. Valve morphology was assessed via TTE or surgical reports. Clinical, imaging, and histopathological data on LV adaptation were compared between patient groups. Results (Table 1) A total of 123 patients were included (mean age of 71±9 years; 50% male), 13% with BAV and 87% with TAV (25 patients with undetermined valve morphology). All BAV cases exhibited the ascending phenotype without root involvement. BAV patients were younger (59±10 vs. 73±6 years, p0.001), predominantly male (75% vs. 46%, p=0.029), with lower prevalence of hypertension (63% vs. 85%, p=0.028). Aortopathy was more prevalent in BAV patients (44% vs. 9%, p0.001). Clinical presentation and AS severity indexes were similar between groups except for higher mean transvalvular gradients (p=0.022) in BAV. Patients with BAV had higher LV mass and positive remodelling at pre-operative CMR (92 74 vs. 71 31 g/m², p=0.008 and 1.04 0.3 vs. 0.92 0.2, p=0.037, respectively). Neither non-invasive myocardial tissue characterization at CMR nor myocardial fibrosis content at biopsy differed among the groups. Surgical bioprosthesis were more commonly implanted in patients with TAV (95% vs 63%, p0.001). BAV patients had higher rates of concomitant ascending aorta grafts at SAVR Conclusion In severe aortic stenosis, clinical presentation is indistinct regardless of valve morphology, except for except higher prevalence of aortopathy in BAV patients. Pressure overload is probably the main driver of LV adaptation, as myocardial tissue characterization is similar in both groups of patients.