Introduction: The Evolution of Risk Assessment in Aortic Regurgitation
Aortic regurgitation (AR) presents a complex clinical challenge, characterized by a chronic volume overload state that necessitates progressive left ventricular (LV) remodeling. For decades, the timing of aortic valve surgery (AVS) has relied heavily on the development of symptoms or the presence of significant LV dilatation and dysfunction. Current clinical guidelines from the American Heart Association (AHA), American College of Cardiology (ACC), and the European Society of Cardiology (ESC) primarily utilize LV end-systolic diameter indexed to body surface area (LVESDi) as a key prognostic marker. However, these guidelines often apply a uniform threshold—typically 25 mm/m²—regardless of the patient’s sex.
As our understanding of cardiac geometry evolves, the limitations of linear measurements (diameters) compared to volumetric measurements (volumes) have become more apparent. Furthermore, growing evidence suggests that cardiac adaptation to valvular disease differs significantly between men and women. This article critically examines the findings of a recent multicenter study published in JAMA Cardiology by Lopez Santi and colleagues, which investigates sex-specific differences in LV remodeling and their associated outcomes in patients with moderate-to-severe AR.
Study Design: A Multicenter Analysis of LV Remodeling
This study was a robust multicenter cohort analysis involving five international centers across the Netherlands, Singapore, Hong Kong, Canada, and Romania. The researchers included 808 patients diagnosed with moderate-to-severe AR and preserved LV ejection fraction (LVEF ≥50%) between December 2003 and December 2022. The cohort consisted of 488 men and 320 women, with a median follow-up period of 7 years.
Patients were excluded if they were symptomatic at baseline, had acute AR, significant concomitant valvular disease, or prior valve surgery. The primary exposure variables were LV dilatation assessed by both linear dimensions (LVESDi) and volumetric dimensions (LV end-systolic volume index, or LVESVi). The primary outcome measured was all-cause mortality, analyzed both during medical management and following AVS.
Linear Dimensions vs. Volumetric Assessment
At the baseline of the study, an interesting discrepancy emerged between linear and volumetric measurements. The mean LVESDi did not differ significantly between the sexes (20 mm/m² for both; P = .77). However, when looking at volumes, men exhibited significantly larger mean LVESVi compared to women (39 mL/m² vs 31 mL/m²; P < .001). This suggests that while linear diameters may appear similar when indexed to body surface area, the actual volumetric burden and remodeling patterns are distinct.
This discrepancy is clinically vital. Linear measurements assume a specific ventricular shape, which may not hold true as the heart remodels. Volumetric assessments, often derived from 3D echocardiography or cardiac MRI, provide a more comprehensive picture of the total remodeling burden, yet they have only recently been integrated into European guidelines with a uniform threshold of 45 mL/m² for both sexes.
Key Findings: Sex-Specific Survival and Mortality Thresholds
The study’s findings regarding survival under medical management were striking. Over the follow-up period, 74 patients died. The adjusted 6-year survival rate was significantly lower in women (80%) compared to men (89%; P = .001). This survival gap suggests that women may be reaching critical risk levels earlier or at different morphological stages than men.
Thresholds for Mortality
Using receiver operating characteristic (ROC) curve analysis and age-adjusted cubic splines, the researchers identified new thresholds associated with increased mortality risk:
- LVESDi: A threshold of 20 mm/m² or greater was associated with increased mortality for both sexes. Notably, this is lower than the 25 mm/m² threshold currently recommended in many guidelines.
- LVESVi (Women): A threshold of 40 mL/m² or greater was associated with mortality.
- LVESVi (Men): A threshold of 45 mL/m² or greater was associated with mortality.
The finding that women have a lower volumetric threshold (40 mL/m²) for mortality compared to men (45 mL/m²) is a pivotal takeaway. It indicates that women may experience adverse outcomes at degrees of ventricular dilatation that are currently considered ‘acceptable’ by guideline standards.
Post-Surgical Outcomes and the Role of Preoperative Volume
A total of 323 patients in the study eventually underwent aortic valve surgery (AVS). Following surgery, the sex-based survival gap disappeared, with survival rates of 85% for women and 89% for men (P = .31). This suggests that timely surgical intervention effectively mitigates the excess risk faced by women.
However, preoperative LVESVi remained a significant predictor of post-operative mortality, specifically showing a sex interaction (HR, 1.03; 95% CI, 1.00-1.06; P = .04). This implies that the degree of volume expansion prior to surgery has a more nuanced impact on women’s long-term recovery and survival compared to men, further emphasizing the need for precision in surgical timing.
Clinical Commentary: The Biological Basis for Sex Differences
Why do women appear to face higher risks at lower volumes? Several biological factors may be at play. Women generally have smaller absolute heart sizes and different ventricular compliance characteristics. Traditional indexing to body surface area (BSA) may not fully account for these differences, as BSA does not perfectly scale with internal cardiac volumes across the sexes. Furthermore, hormonal influences and differences in myocardial fibrosis patterns during remodeling may contribute to women reaching a ‘point of no return’ at lower indexed volumes.
The study also highlights that the currently recommended LVESDi threshold of 25 mm/m² may be too conservative. By the time a patient—male or female—reaches 25 mm/m², they may have already incurred significant, irreversible myocardial damage. The identified 20 mm/m² threshold suggests that earlier surveillance and potentially earlier intervention should be considered to improve long-term prognosis.
Conclusion: Implications for Future Guidelines
The study by Lopez Santi et al. provides compelling evidence that a ‘one-size-fits-all’ approach to aortic regurgitation is inadequate. To optimize patient outcomes, the clinical community must move toward sex-specific risk stratification.
Summary of Recommendations for Practice:
- Lower the threshold for concern: Clinicians should be vigilant when LVESDi reaches 20 mm/m², rather than waiting for the traditional 25 mm/m².
- Adopt volumetric indexing: LVESVi should be routinely measured, as it captures remodeling nuances that linear diameters miss.
- Implement sex-specific cutoffs: Recognize that a LVESVi of 40 mL/m² in a woman carries a similar risk profile to 45 mL/m² in a man.
As we transition toward more personalized medicine, integrating these sex-specific thresholds into clinical guidelines could significantly reduce the mortality gap currently seen in women with aortic regurgitation. Future research should focus on prospective trials to validate whether earlier intervention based on these lower, sex-specific thresholds directly leads to improved survival and quality of life.
References
1. Lopez Santi P, Fortuni F, Bernard J, et al. Sex Differences in Left Ventricular Remodeling for Risk Stratification of Patients With Aortic Regurgitation. JAMA Cardiol. 2026;11(3):239-249. doi:10.1001/jamacardio.2024.5150
2. Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2021;143(5):e72-e227.
3. Vahanian A, Beyersdorf F, Praz F, et al. 2021 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2022;43(7):561-632.