14th World Congress of Cardiology (WCC)
Sydney, Australia
May 2002
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More than 8,000 attendees travelled from various countries, including Argentina, Belarus, and Kenya, to attend the 14th World Congress of Cardiology (WCC), a meeting held 5-9 May 2002 in Sydney, Australia. This congress was the principal meeting of the World Heart Federation, an international body comprising all of the world’s cardiology societies and heart federations. The WCC convenes just once every four years; the next meeting will take place in 2006, in Barcelona, Spain.

Approaches to heart failure diagnosis and prognosis

Advanced imaging in LV dysfunction

Transthoracic Doppler echocardiography is the method most commonly used for documenting cardiac dysfunction at rest—a key criterion for heart failure diagnosis. However, when there is clinical suspicion of heart failure but transthoracic echocardiography does not provide sufficient information, other noninvasive methods can be used. In a session describing advanced, noninvasive imaging methods, Dr. J.-L. Vanoverschelde (Belgium) described dobutamine stress echocardiography; Dr. N. Tanaki reported on fluorodeoxyglucose uptake with imaging by positron emission tomography (FDG-PET); and Dr. J. Lima (USA) provided an update on use of contrast-enhanced magnetic resonance imaging (MRI).

According to the experts, recent study results have established how these new and sensitive methods can be used variously to determine infarct size, recognise microvascular obstruction, and identify tissues that are viable despite ischaemia (see Table 1). Such determinations can, in turn, predict a patient’s response to therapy and even predict long-term prognosis. For example, results of an imaging study could provide a rational basis for removing a patient from the transplant list and using revascularisation instead.

For deciding which method to use, Dr. Vanoverschelde offered a straightforward approach. ‘Start with the simplest, least expensive test; if results are unclear, do additional testing,’ he said. With this strategy, transthoracic echocardiography would be the starting point, and dobutamine stress echocardiography would represent the next level of examination (see video clips). For further investigation, highly sensitive methods such as FDG-PET or MRI may be necessary.

Table 1
Imaging methods for determining LV dysfunction

Method

Benefits/Limitations

Dobutamine stress echo
  • Damaged cardiac tissue that is still viable will respond to challenge with increasing doses of the inotrope dobutamine; results can be used to predict the likelihood of response to revascularisation vs. cardiac death
  • Simplest and least expensive of the advanced imaging methods

Positron Emission Tomography (PET) with FDG perfusion
  • Based on differential rates of radionuclide perfusion and metabolism, this method can be used to ascertain tissue viability
  • Preserved uptake of fluorodeoxyglucose (FDG), despite ischaemia, identifies areas of myocardium that are viable—a condition that can be treated by revascularisation
  • Better reproducibility than echocardiography, although more expensive

Magnetic resonance imaging (contrast-enhanced)
  • Quantitates myocardial necrosis, perfusion, and function
  • Most accurate and reproducible method to determine cardiac volumes, wall thickness, and ventricular mass, but also most expensive
  • Can be used to detect infarct size, microvascular obstruction, lack of functional recovery after MI, and cardiac remodelling
  • May have future applications for measuring response to therapy, especially reversal of remodelling

Use of dobutamine stress echocardiography for assessing left ventricular dysfunction

Normal patient

The baseline video clip shows evidence of normal diastolic filling and normal systolic ejection. For stress testing, dobutamine is infused at increasing doses. Another video clip for this patient demonstrates regular and normal systolic ejection even under dobutamine stress; diastolic filling is also normal.


 Normal cardiac function at baseline  
 


Patient with left ventricular dysfunction

The baseline video clip shows not only evidence of normal diastolic filling, but also impaired systolic ejection. In this patient with severe left ventricular dysfunction, a second video clip shows that diastolic filling remains unchanged under dobutamine stress, while there is further evidence of impaired systolic ejection. Such changes are associated with the presence of nonviable myocardium.

 Severe left ventricular dysfunction at baseline  
 



Video clips' source: Division of Cardiology, Northwestern University Medical School (USA)

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©2002 Failinghearts.com