Left ventricular myocardial work for the prediction of postoperative outcomes in patients with bicuspid aortic stenosis

Chronic elevation of left ventricular (LV) afterload contributes to adverse LV remodeling and myocardial impairment in bicuspid aortic valve (BAV) patients with severe aortic stenosis (AS). Incorporating LV afterload into global longitudinal strain (GLS) analysis, myocardial work facilitates early detection of LV dysfunction. The present study was to evaluate myocardial work in BAV patients with severe AS undergoing surgical aortic valve replacement (SAVR) and to evaluate its prognostic impact on early postoperative outcomes. Between January 2021 and March 2022, BAV patients with severe AS scheduled for SAVR were included and underwent comprehensive transthoracic echocardiography. Quantification of LV myocardial work was performed to obtain LV global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). Clinical outcome was defined as a composite of major cardiovascular events including mortality, myocardial infarction, stroke, acute kidney injury, low cardiac output syndrome and vascular complications during hospitalization or within 30 days after operation. Among 103 BAV patients with severe AS undergoing SAVR (mean age of 65 ± 9 years, 57.3% male), 22 experienced postoperative major cardiovascular events. BAV patients with major cardiovascular events demonstrated lower LV GWI (P < 0.001) and GCW (P = 0.002) along with elder age (P = 0.030), decreased LVGLS (P = 0.026) and right ventricular longitudinal strain (P = 0.019), and higher prevalence of abnormal average E/e' ratio (P = 0.029) than those without major events. Decreased LV GWI and GCW was independently associated with the occurrence of major cardiovascular events (P < 0.01 for adjusted OR). Multivariable logistic regression model including LV GWI demonstrated superior power than the model including LVGLS and yielded best discrimination for BAV patients with and without major cardiovascular events during early postoperative period. Echocardiography-based LV myocardial work overcomes the limitations of LVGLS and presents as a promising novel index for the early detection of functional myocardial damage and the optimization of intervention timing among BAV patients with severe AS.

Recurrent germline mutations as genetic markers for aortic root dilatation in bicuspid aortic valve patients

Bicuspid aortic valve (BAV) is characterized by elevated risk of aortic dilatation and aneurysm. Although genetic susceptibility is suspected to influence on the development of BAV aortopathy, clinical application of genetic markers still needs validation in BAV entities with strictly defined phenotypic features. The 'root phenotype' represents a young, male predominant, and severely aortic regurgitant BAV population prone to aortic root dilatation. The present study launched a two-step genetic survey to evaluate the clinical significance of germline genetic markers in BAV patients. The whole-exome sequencing (WES) cohort consisted of 13 BAV patients with 'root phenotype' under the age of 40 years. We identified 28 different heterozygous missense mutations in 19 genes from the WES cohort, among which six variants (COL1A2 R882C, COL5A1 I1161F, ACVRL1 R218W, NOTCH1 P1227S, MYLK S243W, MYLK D717Y) were identified as pathogenic variants via unanimous agreement of in silico prediction tool analysis, and three variants (C1R I345L, TGFBR2 V216I, FBN2 G475V) were identified as recurrent variants. The panel of nine genetic markers was tested in an independent validation cohort of 154 BAV patients consecutively included from January to May 2018 in our institution. The validation cohort demonstrated 71.4% male predominance and the average age of 57 ± 13 years, among which 26.6% showed aortic root dilatation and 66.9% ascending aortic dilatation. Genetic markers were found in 32 patients, including 18 with C1R I345L, 11 with TGFBR2 V216I, 2 with FBN2 G475V, and 1 with both TGFBR2 V216I and MYLK D717Y. BAV patients carrying these genetic markers demonstrated younger age [(51 ± 12) vs. (58 ± 13) years, P = 0.014], more moderate to severe aortic regurgitation (56.2% vs. 33.6%, P = 0.019), elevated prevalence of mitral valve prolapse (9.4% vs. 0.8%, P = 0.028) and aortic root dilatation (62.5% vs. 17.2%, P < 0.001) but not ascending aortic dilatation than those without these markers. The early-onset 'root phenotype' entities displayed great value for BAV genetic surveys. As one of the promising complements of the current risk stratification system, recurrent germline mutations in TGFBR2, C1R, FBN2 genes could be identified and applied as genetic markers of elevated susceptibility for aortic root but not ascending aortic dilatation among BAV patients.