ECGs lead to fewer heart operations

December 17, 2011 - 05:00

An electrocardiogram (ECG) can be used to predict the course of an individual patient’s disease, resulting in fewer operations, new study shows.

In the future, it may be possible to avoid up to 10-15 percent of the operations to replace constricted heart valves. A Danish researcher has discovered that ECGs can be used to predict the course of heart diseases, and thus make medical staff better at deciding whether a patient really needs surgery. (Photo: Colourbox)

Traditionally, heart patients have been classified according to how constricted their cardiac valve has become, and thereafter whether they could tolerate major surgery to replace the valve.

But the need for such operations is likely to decrease as a result of a new Danish discovery which shows that electrocardiograms (ECGs) can be used to determine more precisely how a patient’s heart actually reacts to the constricted valve. This makes medical staff better at deciding whether a patient really needs surgery.

The discovery has gained the attention and recognition of heart researchers throughout the world and was recently published in one of the world’s leading journals on heart diseases, Circulation.

“As the results make it possible to tailor the treatment to each individual patient, rather than give all patients the same treatment, the prognosis for these patients can be better,” says Anders Greve, a doctor and PhD student at the Copenhagen University Hospital’s Heart Center, who headed the project. “The same degree of constriction of the heart valve does not necessarily require precisely the same treatment, such as surgery to replace the valve.”

Constricted valve can give larger heart

The study is based on ECGs from 1,536 patients, whose progress was monitored by Greve and his colleagues over almost five years.

There are about 1,000 heart valve operations a year in Denmark. If we transfer our results to this figure, we will probably be able to cut the number of operations by 10-15 percent – but that’s a guesstimate.
Dr Anders Greve

All of these patients had sclerosis and initial stages of constriction of the cardiac valve – the part of the heart that prevents blood flowing the wrong way when the heart beats.

Constriction of the heart valve can be regarded as a form of arteriosclerosis in the valve, which affects two to three percent of over-65s living in Denmark. But the number of people affected is growing, says Greve.

The consequences of heart valve constriction can be symptoms of an overloaded heart – such as shortness of breath, chest pains and dizziness. But in some cases the consequences can be graver.

“When the blood is pumped out of the heart it has to pass through the heart valve – and if this is very constricted the heart has to work harder to pump the blood,” explains the researcher. “This strains the heart and can result in an enlarged heart, which is a symptom of the need to relieve the heart through surgery.”

Discovery predicts correct treatment

The new results indicate that the same degree of constriction does not necessarily lead to an enlargement of the heart in all patients.

Facts

About ECGs
• The electrocardiogram (ECG) is more than 100 years old.
• Electrocardiography is a simple, quick and painless method of measuring a heart’s electrical activity.
• The contraction of the heart muscle is controlled by electrical impulses, which the ECG picks up.
• Small electrodes are stuck to the patient’s chest, and possibly also wrists and legs. On the basis of the signals from the electrodes, characteristic curves are shown on a computer screen or printed on a strip of paper.
• These curves – the ECG – show the heart’s rhythm and how the electrical impulses spread in the heart muscle.

“In some cases it can be an advantage to wait before operating,” says Greve. “The risk of complications will be larger if you operate too early than if you don’t operate at all.”

The discovery revolutionises the way in which ECGs can be used – previously, patients with constricted heart valves were classified as mild, moderate or severe cases, and all patients with severe constriction went through major surgery.

“In patients classified as mild or moderate constriction cases, and where the doctor is often in doubt about the best course of treatment, it is important to look at how the heart reacts to the constriction,” adds the researcher. “In other words, doctors must assess the individual patient to improve the prognosis for the patient group as a whole. That’s what we can use this discovery for.”

International network behind study

The results of the study come not only from patients in Denmark, but also from the other Nordic countries, Germany and England, through a network for exchanging research and data on heart diseases.

“The network was vital for achieving a statistically reliable basis for the results,” says Greve. “Without collaboration with the other countries I would not have been able to study the necessary number of ECGs from heart patients meeting the criteria.”

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Translated by
Michael de Laine

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