Decision-Making in Asymptomatic Aortic Regurgitation in the Era of Guidelines: Incremental Values of Resting and Exercise Cardiac Dysfunction
Which echocardiographic measurements at rest and during exercise are predictors of valve surgery among asymptomatic patients with aortic regurgitation?
Comprehensive resting and exercise echocardiography was performed in 159 consecutive patients (50 ± 15 years; 80% male) with isolated moderately severe to severe aortic regurgitation and preserved left ventricular (LV) function (LV ejection fraction >50%, LV end-diastolic dimension ≤70 mm, LV end-systolic dimension ≤50 mm or ≤25 mm/m2) in whom initial management was expectant. Echocardiographic measurements were performed at rest and during exercise. LV and right ventricular (RV) longitudinal strain were analyzed at rest using velocity vector imaging.
Valve surgery was performed in 50 patients (31%) over 30 ± 21 months. After adjustment for age and gender in a multivariable Cox hazard model, higher exercise tricuspid annular plane systolic excursion (TAPSE) (hazard ratio [HR], 0.48; p = 0.001) was associated with freedom from valve surgery, independent of resting LV strain (HR, 1.63; p = 0.005), exercise LV end-diastolic volume (HR, 1.38; p = 0.048), and resting RV strain (HR, 1.69; p = 0.002). In sequential Cox models, a model based on clinical data (chi-square, 20.4) was improved by resting LV strain (chi-square, 30.1; p = 0.001), resting RV strain (chi-square, 49.7; p < 0.001), and further increased by exercise TAPSE (chi-square, 64.4; p < 0.001).
The authors concluded that in asymptomatic aortic regurgitation, resting LV strain, resting RV strain, and exercise TAPSE were independently associated with earlier aortic surgery.
Although limited by its observational nature (patients had to have been referred for clinically indicated exercise echocardiography in the setting of asymptomatic chronic severe aortic regurgitation, and exclusion criteria or incomplete data allowed analysis of only 159 [54%] of 295 identified patients), this is an interesting study. The authors found that measures of resting LV dysfunction (global LV strain), resting RV dysfunction (global RV strain), and exercise RV dysfunction (exercise TAPSE) were independently associated with clinical referral for surgery among patients with asymptomatic chronic severe aortic regurgitation. Existing guidelines for intervention rely on the presence of symptoms, LV systolic dysfunction (LV ejection fraction), or marked LV enlargement. These data suggest that preclinical measures of LV and RV systolic dysfunction could herald the onset of usual clinical indications for intervention. The study does not address whether outcomes would be better if earlier intervention was recommended based on LV strain, RV strain, or exercise TAPSE.
Keywords: Tricuspid Valve, Ventricular Function, Left, Cardiology, Exercise, Referral and Consultation, Heart Ventricles, Echocardiography
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