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Oral Abstract

Oral Abstract Clinical #2- World Impact of Cardiac MRI in Cardiovascular Disease Management

Determinants of Reverse Remodeling in Chronic Severe Aortic Regurgitation: Role of Myocardial Hypertrophy and Extracellular Volume

Friday, January 31, 2025
11:40 AM – 11:50 AM East Coast USA Time
Location: Diplomat Ballroom
Background: Chronic aortic regurgitation (AR) results in myocardial remodeling which is characterized by left ventricular dilatation, myocyte hypertrophy and expansion of the extracellular matrix. This study explored the potential of pre-operative myocardial remodeling to influence reverse remodeling following aortic valve replacement (AVR). Using cardiac magnetic resonance (CMR), we quantified extracellular volume fraction (ECV%) and indexed extracellular volume (iECVol), investigating their association with post-operative remodeling and exercise capacity.


Methods: In a multicenter prospective study (NCT06060171), 81 patients with severe AR undergoing surgical AVR were assessed with paired blood biomarkers, cardiopulmonary exercise testing, and CMR, including T1 mapping at baseline and six months postoperatively.


Results:
Of the 81 patients, 77 underwent AVR, with 72/77 (94%) completing follow-up. The median[IQR] age was 60 [46-70] years, 59 [82%] male, 35 [49%] bicuspid. At 7 [6-8] months after AVR, LVEDVi regressed by 43% (129 to 74ml/m2, p< 0.001), LV end-systolic volume index regressed by 48% (52 to 27ml/m2, p< 0.001) and LV mass index by 20% (96 to 77 g/m2, p< 0.001), Figure 1.



Cellular hypertrophy regressed (66 to 52 ml/m2, -21%) more than iECVol (25 to 21 ml/m2, -16%), resulting in an increase in ECV% (ECV 27.4 [26.0, 29.9] to 28.6% [26.5, 30.8], p< 0.001), Figure 2.



Multivariable analysis revealed that patients with the largest baseline LVEDVi (p=0.002) and greatest regurgitant volume (p< 0.001) had the greatest reduction in LV volume after surgery (Table 1). Associations with higher LVEDVi at follow-up included younger age (p=0.007) and elevated baseline troponin T (p=0.01). Change in LVEDVi was not influenced by iECVol (p=0.81), Table 1. Baseline ECV% was associated with higher follow-up LVMi. Higher ECV% at follow-up was associated with female sex and elevated NT-proBNP.



VO2 max did not significantly change after AVR (22.6 ml/min/kg to 21.0 ml/min/kg, p=0.11). Notably, patients with low baseline VO2 max showed a variable response, with some experiencing stability or improvement, while others, particularly those with initially normal VO2 max, saw a decline.



Conclusion:
Myocardial remodeling in chronic severe AR is highly reversible, but with faster regression of cellular hypertrophy than the extracellular space. Younger patients are at greater risk of incomplete remodeling after surgery, age-specific thresholds may be required. Higher baseline ECV was associated with lesser regression of LV mass, and persistently elevated ECV% after surgery may signal a greater risk of LV decompensation. Despite significant reverse remodeling, improvement in VO2max was not observed at 7 months post-AVR, which may suggest later symptomatic recovery and highlights the complex relationship between symptoms, VO2max, ventricular structure and function.   


Figure 1 Reverse remodeling after aortic valve replacement in chronic severe aortic regurgitation
Figure 1.pdf
Figure 2 Regression of myocardial remodeling at 7 months after aortic valve replacement
Figure 2.pdf