Drug to prevent exercise-induced arrhythmias identified

March 30th, 2009 - 5:56 pm ICT by ANI  

London, Mar 30 (ANI): Vanderbilt University Medical Center researchers have found that a drug can prevent potentially lethal arrhythmias caused due to exercise or stress, called CPVT.

Patients with CPVT experience abnormally rapid heart rates (tachycardia), usually during exercise or stress, and are at risk for fainting and cardiac arrest.

“It’s potentially a breakthrough in the treatment of this rare syndrome,” Nature quoted Bjorn Knollmann, M.D., Ph.D., associate professor of Medicine and Pharmacology, as saying.

For a long time, researchers have been studying the molecular defects that trigger arrhythmias and knew that the disorder is caused by mutations in two genes that encode calcium-handling proteins- the ryanodine receptor and calsequestrin.

In 2006, the group discovered these mutations allows calcium to “leak” out of its storage containers inside heart cells and cause arrhythmias at the cellular level.

The researchers developed a mouse model for CPVT (by eliminating the calsequestrin gene) and proposed using the model to study medications and interventions for the disorder.

When they tried flecainide, a clinically available anti-arrhythmic that is used to treat atrial fibrillation, it gave positive results.

In isolated heart cells, flecainide blocked the ryanodine receptor and the calcium “leak” (the underlying molecular defect in CPVT), and it completely prevented ventricular arrhythmias in the mouse model of CPVT.

“So we knew that this established drug specifically targets the disease mechanism in CPVT,” said Knollmann.

They then tested the drug in two patients, and found that, flecainide (combined with a beta blocker in the boy) prevented exercise-induced ventricular arrhythmias in both patients.

The patients have taken flecainide for more than six months now and are living normal lives.

The study was published in Nature Medicine. (ANI)

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