The effect of aortic valve replacement on left ventricular mass assessed by echocardiography

Sex differences in aortic stenosis: Identification of knowledge gaps for sex-specific personalized medicine

Objectives

This review summarizes sex-based differences in aortic stenosis (AS) and identifies knowledge gaps that should be addressed by future studies.

Background

AS is the most common valvular heart disease in developed countries. Sex-specific differences have not been fully appreciated, as a result of widespread under diagnosis of AS in women.

Summary

Studies including sex-stratified analyses have shown differences in pathophysiology with less calcification and more fibrosis in women's aortic valve. Women have impaired myocardial perfusion reserve and different compensatory response of the left ventricle (LV) to pressure overload, with concentric remodeling and more diffuse fibrosis, in contrast to men with more focal fibrosis and more dilated/eccentrically remodeled LV. There is sex difference in clinical presentation and anatomical characteristics, with women having more paradoxical low-flow/low-gradient AS, under-diagnosis and severity underestimated, with less referral to aortic valve replacement (AVR) compared to men. The response to therapies is also different: women have more adverse events with surgical AVR and greater survival benefit with transcatheter AVR. After AVR, women would have more favorable LV remodeling, but sex-related differences in changes in myocardial reserve flow need future research.

Conclusions

Investigation into these described sex-related differences in AS offers potential utility for improving prevention and treatment of AS in women and men. To better understand sex-based differences in pathophysiology, clinical presentation, and response to therapies, sex-specific critical knowledge gaps should be addressed in future research for sex-specific personalized medicine.

Sex Differences in Aortic Stenosis and Outcome Following Surgical and Transcatheter Aortic Valve Replacement

Aortic stenosis is the commonest valve defect in the developed world and is associated with a high mortality once symptomatic. There is a difference in the way that male and female hearts remodel in the face of chronic pressure overload: women develop a concentrically hypertrophied, small cavity left ventricle (LV), whereas men are more prone to the development of eccentric hypertrophy. At a cellular level, there is an increase in collagen and metalloproteinase gene expression in males suggesting a different regulation of extracellular volume composition according to sex. Male hearts with aortic stenosis appear to have more fibrosis than their female comparators. The trigger for this appears to be in part related to estrogen receptor signaling, but other factors such as renin-angiotensin activation, nitric oxide, and circulating noradrenaline levels may also be implicated. Treatment options include surgical valve replacement (SAVR) and more recently transcatheter aortic valve replacement (TAVR). Female sex may be a risk factor for adverse outcome following SAVR and conversely appears to confer a survival advantage when undergoing TAVR. Whether the lower mortality seen following TAVR in women compared with men (despite their increased age and frailty) reflects their longer life expectancy, smaller annular size (and less post-TAVR aortic regurgitation), more favorable LV reverse remodeling, or more likely, a combination of these factors remains to be established.

The impact of gender on in-hospital mortality and morbidity after isolated aortic valve replacement

The objective of our retrospective investigation was to examine the influence of gender on in-hospital mortality and morbidity after isolated aortic valve replacement (AVR). Between January 1993 and June 2002, 2212 patients (782 females, 1430 males) underwent AVR. Propensity matching was used to adjust for numerous differences in baseline characteristics and perioperative variables between groups. Unadjusted in-hospital mortality was higher in females (27 [3.5%] females versus 23 [1.6%] males; P = 0.005). An analysis using 1:1 matching by propensity score did not find a significant difference in in-hospital mortality [OR (95% confidence intervals), 1.0 [0.4, 2.6]; P = 0.99) or overall morbidity (1.4 [0.7, 2.5]; P = 0.29) between groups. Further analyses, including classification of women and men into quintile groups by propensity scores and logistic regression models with propensity score adjustment, found that females were at increased risk for cardiac morbidity [OR (95% CI), 3.4 [1.1, 10.8]; P = 0.038), but not mortality (0.9 [0.3, 2.5]; P = 0.88) nor other morbidities. These results suggest that there is no greater than a 2.5-fold increase in risk for females compared with males undergoing AVR. Female gender, however, may impart increased risk for cardiac morbidity after AVR.

Evaluation of 17-mm St. Jude Medical Regent prosthetic aortic heart valves by rest and dobutamine stress echocardiography

BACKGROUND

The prosthesis used for aortic valve replacement in patients with small aortic root can be too small in relation to body size, thus showing high transvalvular gradients at rest and/or under stress conditions. This study was carried out to evaluate rest and Dobutamine stress echocardiography (DSE) hemodynamic response of 17-mm St. Jude Medical Regent (SJMR-17 mm) in relatively aged patients at mean 24 months follow-up.

METHODS AND RESULTS

The study population consisted of 19 patients (2 men, 17 women, mean age 69.2 +/- 7.3 years). All patients underwent rest Doppler echocardiography before and after surgery and basal and DSE at follow up (infused at rate of 5 microg/Kg/min and increased by 5 microg/Kg/min at 5 min intervals up to 40 microg/Kg/min). The following parameters were evaluated at rest and/or under DSE: heart rate (HR), ejection fraction (EF), cardiac output (CO), peak and mean velocity and pressure gradients (MxV, MnV, MxPG, MnPG), effective orifice area (EOA), indexed EOA (EOAi), left ventricular mass (LVM), indexed LVM (LVMi), Velocity Time Integral at left ventricular outflow tract (VTI LVOT) and transvalvular (Aortic VTI), Doppler velocity index (DVI). At rest MxPG and MnPG were 29.2 +/- 7.1 and 16.6 +/- 5.8 mmHg, respectively; EOA and EOAi resulted 1.14 +/- 0.3 cm(2) and 0.76 +/- 0.2 cm(2)/m(2); DVI was normal (0.50 +/- 0.1). At follow-up LVM and LVMi decreased significantly from pre-operative value of 258 +/- 43 g and 157.4 +/- 27.7 g/m(2) to 191 +/- 23.8 g and 114.5 +/- 10.6 g/m(2), respectively. DSE increased significantly HR, CO, EF, MxGP (up to 83.4 +/- 2 1.9 mmHg), MnPG (up to 43.2 +/- 12.7 mmHg). EOA, EOAi, DVI increased insignificantly (from baseline up to 1.2 +/- 0.4 cm(2), 0.75 +/- 0.3 cm(2)/m(2) and 0.48 +/- 0.1 respectively). Two patients developed significant intraventricular gradients.

CONCLUSION

These data show that SJMR 17-mm prostheses can be safely implanted in aortic position in relatively aged patients, offering a satisfactory hemodynamic performance at rest and under DSE, with full utilization of its available orifice, suggesting that a possible mild prosthesis-patient mismatch is not an issue of clinical relevance when this small prosthesis is used. Rest and Dobutamine stress echocardiography is a useful and effective means for evaluating prosthesis hemodynamics and for monitoring the expected LVH regression.

Thin Filament Remodeling in Failing Myocardium

While the remodeling process in myocardial failure involves changes in ventricular structure and performance, it is now appreciated that it is also associated with changes in thin filament composition and function. As is discussed, changes at the level thick filament may affect thin filament activation in heart failure. Alterations in actin, troponin and tropomyosin isoform composition do not appear to be significant factors in human heart failure. In contrast, proteolytic degradation of troponin subunits are likely to be playing a functional role in some forms of cardiomyopathy (e.g. ischemic). Finally, phosphorylation of troponin I and troponin T by kinases (most notably protein kinase C) substantially affect thin filament function in failing human myocardium. These findings indicate that functional deficits in thin filament function in failing myocardium are largely reversible and create the potential for future targeted therapies in the treatment of this deadly disease.

Regression of left ventricular mass one year after aortic valve replacement for pure severe aortic stenosis

The aim of the study was to quantify a 1-year change in left ventricular (LV) mass index (MI) and systolic LV function in 30 patients with pure severe aortic stenosis by means of serial 3-dimensional (3-D) echocardiography. To assess the completeness of LVMI regression after 1 year, we compared the postoperative mass of patients with mass values of 30 normotensive control subjects without a history of cardiac disease. Ejection fraction increased from 64 +/- 14% before surgery to 69 +/- 8% at follow-up (p = 0.067), and functional class improved from 2.9 +/- 0.5 to 1.4 +/- 0.5 (p <0.05), with improvement in each patient. During the same period, LVMI regressed by 23.4% (p <0.001). Postoperative LVMI was related to preoperative LVMI (r = 0.82; p <0.001) and baseline ejection fraction (r = -0.5; p = 0.009). LVMI regressed into the normal range in 64% of patients at follow-up. Patients achieving normal mass values did not differ with respect to patient gender, valve type, or valve size. Patients with reduced preoperative LV function had larger volumes (p <0.01), larger mass values (p <0.01), and a trend toward more mass regression (p = 0.062) than patients with normal preoperative function. Although ejection fraction improved after 1 year in all of these patients (p <0.03), they were less likely to achieve normal mass values at follow-up (p = 0.01). Regression of LVMI in patients with pure aortic stenosis is a positive event that occurs in each patient and that is associated with improvement in functional status. LVMI regressed into the normal range in most patients with normal preoperative function. Preoperative LV function, but not patient gender, valve type, or size, was related to normalization of LVMI at follow-up in this selected study population.