European Journal of Cardiovascular Medicine

Aortic valve replacement (AVR) remains the cornerstone treatment for severe aortic stenosis, a condition characterized by significant left ventricular outflow obstruction leading to left ventricular hypertrophy (LVH), reduced cardiac output, and progressive heart failure [1]. The choice of prosthetic valve for AVR, whether mechanical or bioprosthetic, depends on patient-specific factors such as age, lifestyle, and comorbidities [2]. Bioprosthetic valves are increasingly favored for their excellent hemodynamic properties, reduced need for anticoagulation, and lower risk of thromboembolism, especially in elderly populations [3].

The anatomical and functional complexities of the aortic valve make its replacement a challenging yet rewarding intervention [4]. The aortic valve, situated at the junction of the left ventricle and the ascending aorta, consists of three semilunar cusps and ensures unidirectional blood flow during systole while preventing regurgitation during diastole [5]. Severe aortic stenosis imposes a substantial hemodynamic burden on the left ventricle, causing compensatory hypertrophy of myocardial cells. Over time, this hypertrophy leads to diastolic dysfunction and an increased risk of adverse cardiovascular events [6].

This prospective study, conducted at Narayana Hrudayalaya, Bangalore, evaluates the hemodynamic performance and left ventricular mass regression following AVR with bioprosthetic valves [7]. By examining key echocardiographic parameters such as peak pressure gradient (PPG), mean pressure gradient (MPG), left ventricular internal diameters in systole and diastole (LVIDS, LVIDD), and left ventricular mass index (LVMI), the study aims to quantify the clinical and functional benefits of bioprosthetic valve implantation [8].

The study encompasses 100 patients who underwent AVR with bioprosthetic valves between June 2011 and May 2015. These patients were followed for one year postoperatively, with echocardiographic assessments conducted at regular intervals. The findings of this research are expected to contribute significantly to the growing body of evidence supporting bioprosthetic valve usage in severe aortic stenosis, particularly for enhancing patient outcomes and minimizing surgical complications.

This hospital-based prospective study was conducted at Narayana Hrudayalaya, Bangalore, between June 2011 and May 2015. The study aimed to evaluate hemodynamic improvements and left ventricular mass (LVM) regression in patients undergoing aortic valve replacement (AVR) with bioprosthetic valves. A total of 100 patients with isolated severe aortic stenosis were included and followed up for one year postoperatively with serial echocardiographic evaluations.

Inclusion Criteria

1. Patients aged above 40 years.
2. Male and female patients with severe aortic stenosis undergoing isolated AVR.
3. Cases treated exclusively with bioprosthetic valves.
4. Patients classified as New York Heart Association (NYHA) Class I–IV preoperatively.

Exclusion Criteria

1. Patients with associated coronary artery disease.
2. Patients undergoing concomitant mitral or tricuspid valve repair/replacement.
3. Severe left ventricular dysfunction (LVEF < 20%).
4. Patients requiring complex surgeries, such as redo AVR or AVR with ascending aorta replacement.

Data Collection

Preoperative and postoperative echocardiographic data were collected, focusing on the following parameters:

• Left Ventricular Internal Diameter in Diastole (LVIDD)
• Left Ventricular Internal Diameter in Systole (LVIDS)
• Interventricular Septal Thickness (IVST)
• Posterior Wall Thickness (PWT)
• End-Systolic Volume (ESV)
• End-Diastolic Volume (EDV)
• Peak Pressure Gradient (PPG)
• Mean Pressure Gradient (MPG)
• Ejection Fraction (EF)
• Left Ventricular Mass (LVM), calculated using the Troy formula: LVM (gm)=1.05×[(LVIDD + PWT + IVST)3−(LVIDD)3]\text{LVM (gm)} = 1.05 \times \left[ \left( \text{LVIDD + PWT + IVST} \right)^3 - \left( \text{LVIDD} \right)^3 \right]LVM (gm)=1.05×[(LVIDD + PWT + IVST)3−(LVIDD)3]
• Left Ventricular Mass Index (LVMI).

Statistical Analysis

The collected data were analyzed using STATA 11.2. Continuous variables were expressed as mean ± standard deviation, while categorical variables were represented as frequencies and percentages. Pre- and postoperative comparisons of parameters were performed using paired t-tests. A p-value of <0.05 was considered statistically significant.

Patients were followed up postoperatively at regular intervals for one year to assess improvements in echocardiographic parameters and symptomatology. Outcomes such as ICU and hospital stay, mortality, and complications were documented.

This study analyzed the hemodynamic outcomes and left ventricular mass regression in 100 patients undergoing aortic valve replacement (AVR) with bioprosthetic valves. Patients were followed for one year postoperatively, and preoperative and postoperative data were compared to evaluate improvements in clinical and echocardiographic parameters.

Demographics

The study included 70 male and 30 female patients. The majority of patients were in the age group of 60–69 years, followed by the 50–59 years age group. The mean age of the study population was 60.5 ± 9.3 years. Age and gender distribution is summarized in Table 1.

Table 1: Age and Gender Distribution

Echocardiographic Parameters

The following key echocardiographic parameters were assessed preoperatively and one year postoperatively:

1. Left Ventricular Internal Diameter in Diastole (LVIDD):
• Pre-op mean: 46.49 ± 6.54 mm
• Post-op mean: 42.98 ± 4.67 mm
• Reduction: 8.7% (p < 0.00001)
2. Left Ventricular Internal Diameter in Systole (LVIDS):
• Pre-op mean: 30.81 ± 6.86 mm
• Post-op mean: 27.91 ± 4.72 mm
• Reduction: 10% (p < 0.00001)
3. Left Ventricular Mass (LVM):
• Pre-op mean: 241.82 ± 81.38 g
• Post-op mean: 193.62 ± 60.84 g
• Regression: 19.9% (p < 0.00001)
4. Left Ventricular Mass Index (LVMI):
• Pre-op mean: 143.92 ± 43.31 g/m²
• Post-op mean: 115.27 ± 32.97 g/m²
• Regression: 19.58% (p < 0.00001)
5. Ejection Fraction (EF):
• Pre-op mean: 54.27 ± 7.48%
• Post-op mean: 56.34 ± 3.96%
• Improvement: 3.7% (p = 0.002)
6. Peak Pressure Gradient (PPG):
• Pre-op mean: 94.15 ± 29.61 mmHg
• Post-op mean: 23.45 ± 10.89 mmHg
• Reduction: 75.53% (p < 0.00001)
7. Mean Pressure Gradient (MPG):
• Pre-op mean: 59.02 ± 22.46 mmHg
• Post-op mean: 12.54 ± 5.72 mmHg
• Reduction: 79.66% (p < 0.00001)

Figure 1 – showing Age and Gender distribution.

Table 2 compares the Left Ventricular Internal Diameter in Diastole (LVIDD) before and one year after surgery by gender.

Table 2: Comparison of LVIDD (Pre-op and Post-op) by Gender

Figure 2: Comparing LVIDD pre op and post op and in males and females.

Table 3 compares the Ejection Fraction (EF) before and one year after surgery by gender.

Table 3: Comparison of EF (Pre-op and Post-op) by Gender

Figure 3: Comparing EDV pre op and post op in males and females.

Table 4 compares the Left Ventricular Internal Diameter in Systole (LVIDS) before and one year after surgery by gender.

Table 4: Comparison of LVIDS (Pre-op and Post-op) by Gender

Figure 4: Comparing LVIDS pre op and post op and in males and females.

Table 5 compares the Interventricular Septum Thickness (IVS) before and one year after surgery by gender.

Table 5: Comparison of IVS (Pre-op and Post-op) by Gender

Figure 5: Comparing IVS pre op and post op and in males and females.

Table 6 compares the End-Systolic Volume (ESV) before and one year after surgery by gender.

Table 6: Comparison of ESV (Pre-op and Post-op) by Gender

Figure 6: Comparing ESV pre op and post op in males and females.

Table 7 compares the End-Diastolic Volume (EDV) before and one year after surgery by gender.

Table 7: Comparison of EDV (Pre-op and Post-op) by Gender

FIGURE 7: Comparing EDV pre op and post op in males and females.

Table 8 compares the Mean Pressure Gradient (MPG) across the aortic valve before and after AVR surgery by gender.

Table 8: Comparison of MPG (Pre-op and Post-op) by Gender

Figure 8: Comparing MPG pre op and post op in males and females.

Table 9 compares the Peak Pressure Gradient (PPG) across the aortic valve before and after AVR surgery by gender.

Table 9: Comparison of PPG (Pre-op and Post-op) by Gender

Figure 9: Comparing PPG pre op and post op in males and females.

Table 10 compares the Left Ventricular Mass (LVM) before and one year after surgery by gender.

Table 10: Comparison of LVM (Pre-op and Post-op) by Gender

Figure 10: Comparing LVM pre op and post op in males and females.

Table 11 compares the Left Ventricular Mass Index (LVMI) before and one year after surgery by gender.

Table 11: Comparison of LVMI (Pre-op and Post-op) by Gender

Figure 11: Comparing LVMI pre op and post op in males and females.

Table 12 shows the improvement in PWD (Pre-op and Post-op)

Table 12: Comparison of PWD (Pre-op and Post-op)

Figure 12: Comparing PWD pre op and post op in males and females.

Left ventricular hypertrophy (LVH) in aortic stenosis is both a compensatory mechanism for maintaining systolic function and a significant risk factor for cardiac morbidity and mortality [9]. Regression of LVH following aortic valve replacement (AVR) with bioprosthetic valves has been hypothesized to improve survival outcomes, and this study confirms this association, showing significant hemodynamic and structural improvements one year postoperatively [10].

The primary aim of this study was to investigate the degree of left ventricular mass (LVM) regression and associated hemodynamic improvements using echocardiographic parameters one year after bioprosthetic valve implantation [11]. Notably, there were no reports of hemorrhagic or thromboembolic complications, prosthetic valve endocarditis, structural valve deterioration, or reoperations during the follow-up period, underscoring the safety of this intervention [12].

Key Findings

1. Left Ventricular Remodeling:
• LVM regressed significantly from 241.82 ± 81.38 g to 193.62 ± 60.84 g (p < 0.00001).
• Gender-specific analyses revealed that males experienced a reduction from 256.27 ± 87.13 g to 205.21 ± 66.41 g, while females showed a decrease from 208.10 ± 53.51 g to 166.56 ± 32.62 g.
• The overall percentage decrease in LVM was 19.9%, which is consistent with findings from studies such as those by Giovanni Concistrè and García-Bengochea [13].
2. Hemodynamic Improvements:
• Peak Pressure Gradient (PPG): Reduced from 94.15 ± 29.61 mmHg to 23.45 ± 10.89 mmHg (p < 0.00001).
• Mean Pressure Gradient (MPG): Decreased from 59.02 ± 22.46 mmHg to 12.54 ± 5.72 mmHg (p < 0.00001).
• These changes are comparable to results reported by Eichinger WB, where the MPG decreased from preoperative values to postoperative ranges of 10.5–16.0 mmHg based on valve size [14].
3. LVMI Regression:
• LVMI decreased significantly from 143.92 ± 43.31 g/m² to 115.27 ± 32.97 g/m² (p < 0.00001).
• Male patients exhibited a reduction from 150.17 ± 46.62 g/m² to 119.62 ± 36.15 g/m², and female patients from 129.33 ± 30.32 g/m² to 105.10 ± 21.16 g/m².
• The observed 19.58% regression is aligned with studies showing enhanced survival associated with significant LVMI regression [15].
4. Clinical Outcomes:
• Improvements in NYHA class were evident, with most patients transitioning from Class III and IV preoperatively to Class I and II postoperatively [16].
•  

Comparison with Other Studies

The findings of this study align closely with those of Eichinger WB, Giovanni Concistrè, and García-Bengochea, all of which demonstrated significant reductions in LVH and improved hemodynamic parameters post-AVR [17, 18]. For example, Eichinger WB reported a 14.7% decrease in LVMI and improved MPG outcomes based on valve size, while Giovanni Concistrè highlighted significant LVMI regression with sutureless bioprosthetic valves.

Study Limitations

While the results are promising, several limitations must be acknowledged:

1. Surgical procedures were performed by different surgeons, introducing variability in technique.
2. Echocardiographic evaluations were not standardized by a single observer, as patients often presented with existing ECHO results.
3. Confounding factors such as hypertension were not accounted for, potentially influencing outcomes.
4. The study sample size, though statistically significant, remains limited for broader generalizations.
5. Follow-up duration was restricted to one year, necessitating longer-term studies for comprehensive outcome assessments.
6. Hemodynamic performance of individual valve sizes was not specifically evaluated.

Summary

This study confirms that AVR with bioprosthetic valves significantly reduces LVH, improves hemodynamics, and enhances clinical outcomes in patients with severe aortic stenosis. The absence of major complications during follow-up further emphasizes the procedure's safety and efficacy. Future studies should aim to address the identified limitations, include larger populations, and extend follow-up durations to validate these findings and explore long-term benefits [19, 20].

Early aortic valve replacement (AVR) with prosthetic valves in severe aortic stenosis is a highly effective intervention that significantly reduces transvalvular gradients, promotes regression of left ventricular mass (LVM), and improves long-term survival. The findings of this study underscore the critical importance of timely surgical intervention to mitigate the adverse hemodynamic and structural consequences of aortic stenosis.

AVR with bioprosthetic valves offers distinct advantages, particularly in elderly patients, by providing excellent hemodynamic performance while minimizing the risk of hemorrhagic and thromboembolic complications associated with anticoagulant therapy. This makes bioprosthetic valves a safer and more effective choice for patients where anticoagulation is contraindicated or poorly tolerated.

The results of this study reinforce the importance of integrating advanced surgical techniques and individualized care approaches to optimize outcomes for patients with severe aortic stenosis, particularly in the elderly population.

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