Stress echocardiography in dilated cardiomyopathy

Heart failure is a progressive, lethal syndrome characterized by accelerating deterioration [1]. Its estimated prevalence in the USA is around 2.0 %, with an increased prevalence of 6–10 % in patients over 65 years of age [2]. The prognosis of heart failure is uniformly poor if the underlying problem cannot be rectified; half of all patients carrying a diagnosis of heart failure will die within 4 years, and in patients with severe heart failure, more than 50 % will die within 1 year [2]. The actual rate of deterioration is highly variable and depends on the nature and causes of the overload, the age of the patient, and many other factors (Fig. 33.1). Following a period of asymptomatic left ventricular dysfunction that can last more than a decade, survival after the onset of significant symptoms averages about 5 years [3]. Stress echocardiography has a role in initial and advanced stages (Fig. 33.2). In formulating the 2001 document, also endorsed in the 2005 document, the ACC/AHA guidelines developed a new approach to the classification of heart failure, identifying four stages: stage A (at high risk but without structural heart disease, e.g., hypertension), stage B (structural heart disease but without signs and symptoms of heart failure, e.g., previous myocardial infarction or asymptomatic valvular heart disease), stage C (structural heart disease with current or prior symptoms of heart failure), and stage D (refractory heart failure requiring specialized interventions). According to this staging approach, which is conceptually similar to that achieved by staging in other diseases such as cancer, patients would be expected either not to advance at all or to advance from one stage to the next, unless progression of the disease was slowed or stopped by treatment. The recent realization that therapies aimed at symptomatic heart failure may improve outcomes in patients with asymptomatic left ventricular dysfunction has increased the importance of recognizing and treating patients with the asymptomatic stage A and B condition, possibly even more frequent than overt heart failure. In the early stage, in patients with normal left ventricular function, a reduced inotropic reserve can unmask initial damage. In advanced stages, stress echocardiography complements resting echocardiography, identifying a heterogeneous prognostic profile that underlies a similar resting echocardiographic pattern (Table 33.1).