Background:Myocardial contraction fraction (MCF) is a volumetric measure of myocardial shortening independent of left ventricular size and geometry. This multicenter study investigates the usefulness of MCF for risk stratification in low-gradient severe aortic stenosis with preserved ejection fraction.Methods:We included 643 consecutive patients with low-gradient severe aortic stenosis with preserved ejection fraction in whom MCF was computed at baseline and analyzed mortality during follow-up.Results:Throughout follow-up with medical and surgical management (34.9 [16.1–65.3] months), lower MCF tertiles had higher mortality than the highest tertile. Eighty-month survival was 56±4% for MCF>41%, 41±4% for MCF 30% to 41%, and 40±4% for MCF<30% (P<0.001). After comprehensive adjustment, mortality risk remained high for MCF 30% to 41% (adjusted hazard ratio, 1.53 [1.08–2.18]) and for MCF<30% (adjusted hazard ratio, 1.82 [1.24–2.66]) versus MCF>41%. The optimal MCF cutoff point for mortality prediction was 41%. Age, body mass index, Charlson index, peak aortic velocity, and ejection fraction were independently associated with mortality. MCF (χ² to improve 10.39; P=0.001), provided greater additional prognostic value over the baseline parameters than stroke volume (SV) index (χ² to improve 5.41; P=0.042), left ventricular mass index (χ² to improve 2.15; P=0.137), or global longitudinal strain (χ² to improve 3.67; P=0.061). MCF outperformed ejection fraction for mortality prediction. When patients were classified by SV index and MCF, mortality risk was low when SV index was ≥30 mL/m² and MCF>41%, higher for patients with SV index ≥30 mL/m² and MCF≤41% (adjusted hazard ratio, 1.47 [1.05–2.07]) and extremely high for patients with SV index <30 mL/m² (adjusted hazard ratio, 2.29 [1.45–3.62]).Conclusions:MCF is a valuable marker of risk in low-gradient severe aortic stenosis with preserved ejection fraction and could improve decision-making, especially in normal-flow low-gradient severe aortic stenosis with preserved ejection fraction.

中文翻译：

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保留射血分数的低梯度主动脉瓣狭窄风险分层的心肌收缩分数

背景：心肌收缩分数 (MCF) 是心肌缩短的体积测量，与左心室大小和几何形状无关。这项多中心研究调查了 MCF 在射血分数保留的低梯度重度主动脉瓣狭窄风险分层中的有用性。随访期间的死亡率。结果：通过内科和外科管理（34.9 [16.1-65.3] 个月）的随访，较低的 MCF 三分位数比最高的三分位数死亡率更高。MCF>41%的80个月生存率为56±4%，MCF 30%～41%为41±4%，MCF<30%为40±4%（P<0.001)。综合调整后，MCF 30% 至 41%（调整后的风险比，1.53 [1.08-2.18]）和 MCF<30%（调整后的风险比，1.82 [1.24-2.66]）与 MCF>41% 的死亡率风险仍然很高. 死亡率预测的最佳 MCF 截止点是 41%。年龄、体重指数、查尔森指数、主动脉峰值流速和射血分数与死亡率独立相关。MCF（χ ²提高 10.39；P = 0.001）比每搏量 (SV) 指数（χ ²提高 5.41；P = 0.042）、左心室质量指数（χ ²提高2.15; P = 0.137），或整体纵向应变（χ ²改进 3.67；P = 0.061）。MCF 在死亡率预测方面的表现优于射血分数。当患者按 SV 指数和 MCF 分类时，当 SV 指数≥30 mL/m ²且 MCF>41%时死亡风险较低，SV 指数≥30 mL/m ²且 MCF≤41% 的患者死亡风险较高（调整风险比率，1.47 [1.05–2.07]) 并且对于 SV 指数 <30 mL/m ^{2 的}患者极高（调整后的风险比，2.29 [1.45–3.62]）。结论：MCF 是低梯度重度患者的有价值的风险标志物射血分数保留的主动脉瓣狭窄，可以改善决策，尤其是正常流量低梯度的严重主动脉瓣狭窄，射血分数保留。