Background: Aortic valve replacement (AVR) is the treatment of choice in patients with severe symptomatic aortic stenosis (AS). Patients with a low left ventricular ejection fraction (LVEF) represent a challenge for evaluation and therapeutic decision. Dobutamine stress echocardiography (DSE) allows the distinction to be made between fixed low-flow/low-gradient (LF/LG) AS and pseudosevere AS.
Methods: Between 2001 and 2014 a retrospective analysis was conducted of patients who underwent DSE to investigate severe AS. DSE was performed in 3- to 5-min steps up to a maximum dose of 20 μg/kg/min. Parameters evaluated at baseline and at each step of DSE included: left ventricular enddiastolic volume (LVEDV) and left ventricular endsystolic volume (LVESV), maximum gradient (MaxG), mean gradient (MG) and aortic valve area (AVA). AS was considered to be severe if the AVA at peak dose was ≤1 cm2. Patients were allocated to two groups according to their therapy: group 1 received only medical treatment, while group 2 underwent AVR. The average follow up was 51.5 ± 4.4 months.
Results: A total of 41 patients (28 males, 13 females; mean age 71.7 ± 8.3 years) was analyzed. Severe AS was diagnosed in 34 patients (83%). Baseline echocardiographic characteristics were: AVA 0.7 ± 0.2 cm2, MaxG 42.0 ± 9.1 mmHg, MG 25.6 ± 6.4 mmHg, LVEF 33.1 ± 8.4%, LVEDV 149.6 ± 44.5 ml, and LVESV 104.0 ± 42.6 ml. At peak DSE, AVA was 0.8 ± 0.2 cm2, MaxG 62.7 ± 18.2 mmHg, MG 38.1 ± 11.6 mmHg, LVEF 42.2 ± 9.9%, LVEDV 142.6 ± 43.85 ml, and LVESV 89.7 ± 37.4 ml. Nineteen patients were allocated to group 1, and 22 to group 2. In group 2, two patients underwent transcatheter aortic valve implantation (TAVI) and 20 had surgery. Mortality in group 1 was significantly higher than in group 2 (78.9% versus 27.3%). A Cox proportional hazard model analysis showed that no-intervention was the only predictor of mortality (unadjusted to age; hazard ratio (HR) 5.13, 95% confidence interval (CI) 1.96-13.44, p = 0.001; adjusted to age - HR 4.01, 95% CI 1.46-11.01, p = 0.007).
Conclusions: LF/LG AS has a poor prognosis without intervention. DSE allows the lesion severity to be established. In the present study intervention was a predictor of survival during follow up.