Halifax-led heart study looks at ventricular tachycardia
Dalhousie University study finds 1 treatment decreases rate of irregular rhythm returning by about 28%
A Halifax-led study could lead to better life-saving treatment for people suffering from a deadly heart condition.
The clinical trial involved 259 patients at 22 medical centres around the world who suffer from a condition known as ventricular tachycardia, which can result in a dangerous, abnormal heart rhythm and affects about 50,000 Canadians.
The study considered two treatment options. It found that one option, which used a wire inserted into blood vessels to stop short circuits, was 28 per cent more likely to prevent the problem from reoccuring than the second option of raising drug doses.
Ventricular tachycardia is usually caused by a scar in the heart, according to Dalhousie Medical School's Dr. John Sapp, who headed the study that was published this week in the New England Journal of Medicine.
"This is a very difficult disease to treat," he said.
"It's when the lower chambers of the heart — which do the pumping — take over and start beating on their own instead of following the lead of the upper chambers, who are supposed to be in control."
Rhythm out of control
He said the irregularity can be life threatening if is is too quick, if there's been a prior heart attack, or if it happens inside a diseased or otherwise weakened heart.
Inside the scar there are bits of heart muscle that aren't completely damaged and which still have electrical properties, even though they don't help the heart beat, he said.
"Those electrical properties can cause short circuits that mess up the heart rhythm."
2 options when arrhythmia occurs
All patients involved in the study had been on some sort of antiarrhythmic drug, but the arrhythmia returned.
When this situation occurs, there are two options: either increase the amount of drug the patient takes or perform an ablation. The Dalhousie study looked at which would result in the best outcome.
During ablation, doctors insert a wire into the blood vessels leading to the heart in order to find those short circuits.
"One of our wires has a special tip on it that we can use to cauterize or ablate the short circuits," said Sapp.
Both treatments carry risks
Sapp cautions that both procedures have risks of complications that must be individually weighed for each patient.
"Most clinicians use medication as their first-line treatment but the medications aren't wonderful for this and they do have some risks," he said.
Such risks may include increased skin sensitivity to sunlight. Medication can also affect the thyroid gland, as well as the liver, lungs and nerves.
The study found that choosing the ablation procedure over more aggressive medication treatment decreased the rate of irregular rhythm returning by about 28 per cent.
"Everybody in Nova Scotia knows somebody — an uncle, cousin, friend — who has had a heart attack ... and then one day they just die suddenly," said Sapp.
"A lot of times we just think that they had a massive heart attack, when in fact, a lot of times it's the rhythm giving out and that's caused by ventricular tachycardia."
Doctors starting using ablation techniques in the early 1990s but the practice has grown quite a bit within the last 15 years or so, said Sapp.
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