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.
- A full discussion of these techniques is beyond the scope of this article and the reader is referred to an excellent review on the subject by Nagueh, et al., in the American College of Cardiology Current Journal Review (Jan/Feb 2002).