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Impact of Sex and Transvalvular Flow After Surgical AVR
Study Questions:
What is the impact of preoperative transvalvular flow and pressure gradient on mortality following surgical aortic valve replacement (AVR) for severe aortic stenosis (AS), and how are these associations influenced by patient sex?
Methods:
Clinical, echocardiographic, and outcome data were collected prospectively on 1,490 patients with severe calcific AS and preserved left ventricular ejection fraction (LVEF) who underwent surgical AVR between 2004-2015 at the Quebec Heart and Lung Institute. Patients were excluded when the primary indication for AVR was not severe AS (such as aortic regurgitation, infective endocarditis, coronary artery bypass grafting), for LVEF <50%, for redo surgeries, and in cases with incomplete echocardiographic data. The population was divided into two groups: normal flow (NF), with indexed stroke volume (SVi) ≥35 ml/m2 and low flow (LF) with SVi <35 ml/m2, also referred to as paradoxical low flow (PLF) due to its occurrence despite normal LVEF. These groups were further stratified based on mean pressure gradient >40 mm Hg (HG) or <40 mm Hg (LG). Cumulative all-cause mortality, the primary endpoint, was determined for each of the four flow-gradient patterns: NF/HG, NF/LG, LF/HG, and LF/LG.
Results:
There were 167 deaths during a median follow-up of 2.42 years. Patients with PLF had greater all-cause mortality than those with NF (odds ratio, 1.60; 95% confidence interval [CI], 1.17-2.18), while no difference was seen in LG and HG groups. LF/HG (17% of total patients) was the only flow-gradient pattern associated with increased mortality (hazard ratio [HR], 2.0; 95% CI, 1.33-3.03). After multivariate analysis, age, New York Heart Association functional class III/IV, diabetes, chronic kidney disease, and chronic obstructive pulmonary disease were independent predictors of mortality. PLF and LF/HG remained independently associated with mortality (HR, 1.53 and 1.84, respectively; p < 0.01). Finally, the authors observed significant interactions between sex, transvalvular flow, and flow-gradient pattern. PLF and LF/HG were associated with increased mortality in women but not men when using the standard cutoff of 35 ml/m2 for SVi. When sex-specific thresholds were used (40 ml/m2 for men and 32 ml/m2 for women), PLF and LF/HG were found to be independently associated with higher mortality in both sexes.
Conclusions:
- Low transvalvular flow (PLF) and LF/HG flow-gradient pattern are associated with increased all-cause mortality after surgical AVR for severe AS.
- PLF and LF/HG are predictors of post-surgical mortality in both men and women only when sex-specific thresholds for SVi are used.
Perspective:
This article has several major implications. First, the authors find that SVi (PLF vs. NF) but not mean pressure gradient is a significant predictor of adverse outcomes in patients with severe AS, indicating that cardiac function may be more predictive than degree of valve stenosis. Second, flow-gradient pattern, a recently-defined and underutilized classification, may have additional prognostic value. Early surgical intervention may be indicated in patients with PLF but low gradient, given their superior outcomes in comparison to LF/HG. Finally, sex-specific SVi cutoffs may be needed to properly define PLF such that it retains its predictive value in both sexes.
Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Valvular Heart Disease, Aortic Surgery, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Acute Heart Failure, Interventions and Imaging, Interventions and Structural Heart Disease, Echocardiography/Ultrasound
Keywords: Aortic Valve Stenosis, Cardiac Surgical Procedures, Diabetes Mellitus, Echocardiography, Heart Failure, Heart Valve Diseases, Kidney Diseases, Pulmonary Disease, Chronic Obstructive, Stroke Volume, Transcatheter Aortic Valve Replacement
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