Diagnostic Impact of Low-dose Dobutamine Echocardiography in Low-flow Low-gradient Aortic Stenosis

Diagnostic Impact of Low-dose Dobutamine Echocardiography in Low-flow Low-gradient Aortic Stenosis

When aortic valve-area is <1.0cm2 and transvalvular mean-gradient is >40mmHg, the diagnosis of severe aortic stenosis (AS) is straightforward. However, some patients present with an apparently reduced valve-area, despite transvalvular-gradient <40mmHg; Low-flow, low-gradient aortic stenosis (LFLG AS). When a patient with LFLG AS also presents with LVEF <50%, guidelines recommends performing a Low-Dose Dobutamine-echocardiography (LDDE) to confirm true-severe AS. However, nearly 30% of patients with LFLG AS do not show an adequate respond to Dobutamine. More commonly, patients present with the combination of LFLG AS, despite LVEF≥50%. In this group of patients the use of LDDE remains undisclosed.

The purpose of this study is to examine the safety and diagnostic usefulness of LDDE in patients with LFLG AS with LVEF≥50%. Furthermore we will examine factors associated with inadequate response to LDDE.

150 symptomatic and/or asymptomatic patients with LFLG and LVEF≥50% and a control group with LVEF<50% will be enrolled at the Department of Cardiology, OUH. Patients will undergo clinical evaluation including LDDE, blood analyses, CT-scan and cardiac Mri.

Only a limited number of studies examine the possible use of LDDE in patients with LFLG AS and LVEF≥50% and no study has been performed documenting the safety and feasibility.

Inclusion Criteria:

1. Low-flow (SVi<35 ml/m2) low-gradient (mean gradient <40 mmHg) AS with estimated AVA<1.0 cm2 referred to the Department of Cardiology, Odense University Hospital.
2. Age > 18 years.
3. Signed informed consent.

Exclusion Criteria:

1. Other moderate-severe valvular heart disease.
2. Unwilling to participate in the study.
3. Poor echocardiographic window.
4. Inability to follow-up due to temporary citizenship Registration Number (CPR-Number) or emigration within the study period.
5. Pregnant women.
6. Patients with severe chronic renal failure (eGFR<40 ml/min) will not undergo cardiac MRi or CT angiography.
7. Known contrast allergy.