Linda D Gillam Director of Echocardiography, Hartford Hospital, and Associate Professor of Medicine, University of Connecticut School of medicine

Originally printed in:
» US Cardiology 2004 - August 2004

Prognosis

A number of parameters that can be determined echocardiographically have been identified as negative prognostic factors in patients with heart failure and systolic dysfunction. Reduced left ventricular ejection fraction (less than 25%) is a strong negative prognostic factor and impaired right ventricular systolic performance is also an important independent predictor of increased mortality and morbidity.

Echocardiographic methods of assessing right ventricular systolic performance are not as well developed as those for the left ventricle, due in part to the complex geometry of the right ventricle.

Two-dimensional echocardiographic techniques include the tricuspid annular plane excursion, fractional area change, and systolic velocities defined by Doppler tissue imaging. Recently developed realtime 3-D echocardiographic techniques promise to be extremely valuable tools for assessing the right heart.

The myocardial performance index as applied to both right and left ventricular function has also been identified as being prognostically important, as has the presence of functional mitral regurgitation and the response of the left ventricle to dobutamine stress. It is notable that patients who do not demonstrate myocardial contractile reserve with dobutamine infusion do less well than those in whom recruitable myocardial systolic performance is demonstrable.

One of the most robust echocardiographic markers of a poor prognosis is a restrictive mitral inflow pattern characterized by a dominant E wave (E to A reversal) and a shortened E wave deceleration time. Persistence of this filling pattern despite aggressive medical management is particularly ominous.

Guide to Therapy

Echocardiography can also be extremely valuable as a tool to guiding therapy. In addition to providing a number of parameters that can be used to measure the impact of medical therapy, it may also identify patients for specific surgical interventions such as palliative mitral valve repair, placement of left ventricular assist devices and/or ventricular remodeling surgery.

Echocardiography plays a unique role in the setting of cardiac resynchronization therapy (CRT) with biventricular pacing. This technique improves function and survival in patients with Class III–IV heart failure despite optimal medical management and is offered to patients with QRS prolongation and a left ventricular ejection fraction of less than 35%. The superb temporal and spatial resolution of echocardiography makes it uniquely able to measure the degree of ventricular asynchrony, which, in turn, appears to identify patients who are most likely to benefit from this expensive technology. Multiple echocardiographic modalities have been used for this purpose including those based on M-mode, 2-D, Doppler tissue imaging and derived strain techniques.

Echocardiography has also been used to guide left ventricular lead placement and for optimization of atrio-ventricular (AV) and interventricular (VV) delays following implantation. Furthermore, a number of echocardiographic parameters have been used to monitor the response to therapy and are included in many of the trials in this field. These include many of the methods discussed in earlier paragraphs of this review.

This is an area of active investigation in the echocardiographic, pacing and heart failure communities, bringing experts from these three fields together.

Echocardiography as a Tool in Small Animal Models

Technologic advances in echocardiography have resulted in the availability of echocardiographic methods of assessing ventricular function and perfusion in small animal models of heart failure.These include transgenic mice in which resting heart rate exceeds 600 beats per minute (bpm).

Summary

Echocardiography is enormously valuable in the diagnosis and management of patients with heart failure. At the time of initial patient evaluation, this technique is easily able to determine whether the primary abnormality is systolic or diastolic dysfunction and exclude underlying primary valve dysfunction or congenital heart disease. It is able to provide insight into the pathophysiology of heart failure in individual patients and has proven valuable in defining the natural history of the disease. It can provide a non-invasive assessment of hemodynamics and may help identify patients with a poor prognosis.

Finally, it may help guide the selection of patients for therapeutic intervention, and plays a critical role in cardiac resynchronization therapy, identifying patients most likely to benefit from device implantation and optimizing device settings post-implantation.