Abstract 667: Valvulo-Arterial Impedance Predicts Postoperative Change in Ejection Fraction in Patients Undergoing Aortic Valve Replacement for Aortic Stenosis
Background: Evidence suggests that the pathophysiology of aortic stenosis (AS) is not isolated to the valve but also involves changes in the arterial circulation affecting systemic arterial compliance as well as changes in the left ventricle. Valvulo-arterial impedance (Zva) incorporates systemic arterial compliance and is therefore thought to represent a more accurate estimate of the global afterload faced by the LV in AS. Zva has been proposed as an important contributor to the severity of AS and might provide the ability to predict LVEF changes after valve surgery for AS. We evaluated whether the change in LVEF following Aortic valve replacement (AVR) for AS can be predicted by preoperative Zva.
Methods: We retrospectively examined the pre and postoperative echocardiographic and clinical data of all patients undergoing AVR for AS between Jan, 2003 and Dec, 2008. Zva was calculated noninvasively by dividing the estimated LV systolic pressure (brachial systolic pressure + mean transvalvular gradient by Doppler) by the stroke volume index from LVOT.
Results: We enrolled 73 patients; mean age 72 and 46 (63%) males. Majority (55 (75%)) received a bioprosthetic valve. Patients were divided into three groups; low (≤3.5 mmHg/ml/m2), medium (3.5– 4.5) and high (≥4.5) preoperative Zva values. The prevalence of diabetes, CAD, hypertension, dyslipidemia, obesity and smoking was similar in the three Zva groups. Baseline EF was lower in high and medium Zva groups compared to the low Zva patients (56±6 and 59±7 versus 69±7; P=0.01 and 0.039). EF increased more in the high Zva cohort than in medium and low Zva groups (10.7 versus 2.8 and −2.1; P=0.02 and 0.007), including the subgroup analysis for patients with preoperative EF≥55%. LVEF increased in 83% of high Zva patients compared to 60% and 29% of medium and low Zva patients. A strong inverse correlation (r=−0.73) was observed between the change in Zva after AVR and the postoperative change in EF.
Conclusions: Improvement in LVEF following AVR for AS occurs more frequently and to a greater degree in patients with a high preoperative Zva. A good correlation exists between the change in Zva and change in EF after valve surgery.