Clinical Trial: Improving Echo Measurements in the Diagnosis of Aortic Stenosis

Study Status: Completed
Recruit Status: Completed
Study Type: Observational

Official Title: Improving The Quality Of Echocardiographic Imaging Measurements In The Diagnosis Of Severe Aortic Stenosis

Brief Summary: Aortic stenosis is a common valvular heart disease, affecting mainly people over age 60. It is characterized by years to decades of slow progression followed by rapid clinical deterioration and a high death rate once symptoms develop. The onset of symptoms confers a poor prognosis: patients die within an average of five years after the onset of angina, three years after the onset of syncope, and two years after the onset of heart failure symptoms. The overall mortality rate is 75% at three years without surgery. Drug therapy for it remains ineffective, and aortic valve replacement is the only recommended long-term treatment.

Detailed Summary:

OBJECTIVES Primary Objective The primary objective of this study is to review the current practice of transthoracic echocardiogram (TTE) imaging measurements in conjunction with computerized tomography (CT) and to standardize these measurements in order to improve the accuracy of the diagnosis of aortic stenosis (AS).

Secondary Objective The secondary objective of the study is to define the true incidence of low flow, low gradient severe aortic stenosis with a normal ejection fraction (EF).

BACKGROUND In recent years, the advancement of medical technology has allowed certain patients to undergo less invasive approaches for aortic valve replacement such as transcatheter aortic valve replacement (TAVR). In order to appropriately select treatment options, anatomical measurements must be accurately obtained utilizing TTE and CT.

According to the American College of Cardiology/American Heart Association Practice Guidelines, the severity o f aortic stenosis is determined by definitions of aortic jet velocity, mean pressure gradient, and aortic valve area (AVA) (Bonow, 2008).

Mild Moderate Severe AVA (cm2) 1.5 1.0 - 1.5 < 1.0 Mean gradient (mmHg) < 25 25 - 40 > 40 Jet velocity (m/s) < 3.0 3.0 - 4.0 > 4.0

Rationale for study

Of greatest interest to this study is the calculation of the AVA in the diagnosis of the severity of aortic stenosis. Since the area cannot be directly measured from echocardiographic images, it is calculated based on the diameter across the left ventricular outflow tract (LVOT) as measured via TTE. The preferred modality for measuring AVA is the continuity equation:

Echocardiography assessments of Aortic stenosis are technician dependent and can vary while CT evaluations are consistent and do not vary by user. This study will retrospectively examine subjects that have undergone both assessments as a workup for definitive aortic valve treatment. The anatomical measurements obtained from CT will be used to recalculate Aortic Valve Area utilizing the standard formulas and gradients/velocities obtained from echocardiography. Patients will be reclassified appropriately into "severe and non-severe" AS according to the new calculations. The results of this will be analyzed to establish standardized ranges for measurements to prevent over or under measuring aortic valve anatomy during these tests (Echo and CT).