The relationship between ascending aortic diameter with left atrial functions and left ventricular mass index in a population with normal left ventricular systolic function

Ascending aortic dilatation is a common clinical issue. In the present study, we aimed to evaluate the relationship between ascending aortic diameter with left ventricular (LV) and left atrial (LA) functions, and LV mass index (LVMI) in a population with normal LV systolic function.

culatory performance. 8,9 To maintain the effective arterial-ventricular coupling throughout the life, LV adapts to progressive arterial stiffness and afterload by increased systolic elastance, concentric remodeling, and hypertrophy. However, this adaptation may lead to increased oxygen demand and decreased cardiovascular reserve, resulting in heart failure (HF). 10 The presence of common risk factors associated with remodeling in the aortic wall and the decrease in elasticity due to remodeling may cause aortic dilatation and deterioration in LV structure and function. Although LV dysfunction has a decisive impact on adverse cardiovascular outcomes, left atrial (LA) dilatation and dysfunction are also substantial. Both circumstances often coexist in a cause-effect relationship. 11 This condition can be demonstrated by increased LV wall thickness, impaired LV systolic and diastolic functions, increased LA volume, and decreased LA strain. 12,13 Although similar clinical studies exist in the literature, we could find no research showing the mentioned relationship using LV and LA strains in population with normal LV systolic function. Therefore, we aimed to evaluate the relationship between ascending aortic diameter with LV and LA functions, and left ventricle mass-index (LVMI) in this population.

METHODS
The present research is a prospective, single-center, observational cross-sectional cohort study, and included 127 consecutive participants with normal LV systolic functions. All patients had given informed consent and the local ethics committee approved the study. DM and HT were defined according to the current guidelines. 14

RESULTS
A total of 127 participants (51 male and 76 female) with a mean age of 43 There was a negative correlation between aortic diameter and LV systolic functions (LVEF r = −.516, p < .001; GLS r = −.370). In addition, there was a strong positive correlation between aortic diameter with LV wall thickness, LVMI (r = .745, p < .001), and systolic and diastolic diameters ( Table 2 and Figure 1).
Remodeling of the LV wall leads to impaired diastolic functions. We found a negative correlation between aortic diameter and Mitral E, Em, E/A ratio, and a positive correlation with MPI, Mitral A, Am, E/Em ratio (Table 2 and Figure 2). These findings showed a correlation between an increase in aortic diameter and an impairment in diastolic parameters.
In addition, aortic diameter tended to increase with epicardial adipose tissue volume. This result was consistent with the relationship between epicardial adipose tissue content and LV and aortic diameters obtained in previous studies.
Deterioration in LV diastolic and systolic functions affects the LA structure and function. In the present study, aortic diameter increase was positively correlated with LAVI and LA Total Empty Volume, while negatively correlated with LA Total Empty fraction and LA Passive Empty Fraction (Table 2 and Figure 3). In linear regression analysis, age, PW, LVSD, LVMI, LAPaEmVol, and LAPaEmFr were independently associated with the aortic diameter (Table 3).

DISCUSSION
In the present study, we observed a strong correlation between ascending aortic diameter with LV and LA functions, and LVMI in individuals with normal LV systolic function.
Aortic size increases throughout life, accompanied by loss of compliance and wall stiffness, and this process ultimately leads to arterial dilatation. An increase in ascending aortic diameter is an indicator of cardiovascular and all-cause mortality. 18 Proximal aortic dilatation can be considered an indicator of the effect of cardiovascular risk factors with prognostic importance.
The pathogenesis of ascending aortic dilatation includes various factors with local or systemic effects. Mechanisms such as hemodynamic strength, transmural inflammation, remodeling of the extracellular matrix, and familial predisposition are among these factors. [19][20][21][22][23] There is no particular evidence for the predictive role of aortic dilatation on cardiovascular mortality. Most studies have examined a combination of non-fatal and fatal stroke, coronary events, and HF requiring hospitalization as an endpoint. [24][25][26][27][28][29][30] The Framingham Heart Study showed that participants with larger aortic root diameters experienced more HF-related events over an 8-year follow-up period. 24 Consistent with the previous researches, a negative correlation was observed between aortic diameter and LV systolic functions in the present study.
The LA wall is relatively thin, similar to the aortic wall. 31 34 To ensure normal cardiac performance, the LV must be able to provide an adequate stroke volume and be filled without requiring high LA pressure. These (systolic and diastolic) functions should meet the body's needs both at rest and during exertion. 35 Recently, an independent relationship between the index of diastolic function which is defined as deceleration time/peak E velocity ratio, and aortic root size, has been demonstrated in a populationbased sample 36 and in a HT cohort study. 37 All these findings suggest that there is a common pathway in the pathogenesis of ARD and LV diastolic dysfunction. This connection was further supported by the independent relationship of aortic root size observed in the entire study population, reflecting LV relaxation/filling, which is a valid representation of LA diameter and volume.
In the present study, LV wall thicknesses and LVMI were associated with aortic diameter. Echocardiographic LV hypertrophy (LVH) is an important biomarker of hypertensive heart disease and a strong predictor of cardiovascular morbidity and mortality. [38][39][40][41][42] In particular, the relationship between aortic dilatation and LVH highlights the role of combined arterial-ventricular remodeling. These finding shows that remodeling in the aortic and LV wall is interrelated. This is may be due to the factors that cause remodeling in the aortic wall also play a role in the remodeling of the LV wall. Another possible reason is that remodeling in the aortic wall triggers remodeling in the LV wall by creating an additional afterload or disrupting the physiological relationship between the aorta and the LV wall. Findings from the general population and hypertensive cohorts have shown that the incidence of cardiovascular events increases when LV remodeling and aortic wall remodeling proceed in parallel. 26,29 In nine studies that found a positive relationship between aortic diameter and cardiovascular events, the inclusion of LV mass in the statistical findings eliminates the prognostic importance of aortic diameter in predicting HF, non-fatal and fatal cardiovascular events, and all-cause mortality in hypertensive patients using anti-hypertensives. 26 An association between sinus Valsalva dilatation and LV mass has been reported in previous studies. [44][45][46] It has been shown that an increase in LV mass can be detected in the dilatation of the ascending aorta, supporting our findings. 47

CONCLUSION
In the current study, we observed a strong correlation between ascending aortic diameter with LV and LA functions, and LVMI in individuals with normal LV systolic function. It would be beneficial to evaluate ascending aorta diameter in clinical practice due to its prognostic importance.

Limitations
The study was single-center and was conducted with a limited number of patients. Aortic diameter imaging was performed only with 2D echocardiography. Evaluation with invasive or advanced imaging methods will reduce the margin of error. Large population studies are needed to confirm the findings and clarify the underlying mechanisms.