New therapy may be tested on humans within a year

CLEVELAND (USA) - Cardiac arrhythmia is a heart dancing dangerously out of step.

It is the principal reason 400,000 Americans die each year of heart disease. People who have it can’t pump blood in a synchronized fashion, setting up a chain reaction that not only weakens the heart but also leads to abrupt loss of consciousness and, often, death.

A novel therapy, tested in animals at Cleveland’s MetroHealth Medical Center with encouraging results, may be ready for human trials within a year.

The experimental drug - so new that it still goes by the numerical name ZP123 - selectively opens the specialized channels for electrical communication between neighboring cells in the heart.

’Normally, during a heart attack, these junctures close,’ said Dr. David Rosenbaum, director of the Heart and Vascular Research Center at Case Western Reserve University School of Medicine and chief of cardiology at MetroHealth.

The MetroHealth study, which was paid for by Danish drug maker Zealand Pharmaceuticals, the American Heart Association and the National Institutes of Health, appeared in Wednesday’s issue of the journal Circulation.

In recent years, doctors have controlled the condition by inserting a tiny metallic device called an ICD, short for implantable cardioverter defibrillator.

The oval-shaped device, about the size of a silver dollar, helps resuscitate the heart when an arrhythmia starts. Vice President Dick Cheney has had an ICD for about two years.

But the ICDs do nothing to alter the progression of heart disease so researchers have long hoped to find a drug or combination of drugs that could achieve the same goal as an ICD as well as alleviate some of the symptoms that cause the tick of a heart to suddenly become a ticking time bomb.

Zealand, which developed the peptide or small protein, suggests the drug can reduce the risk of a cardiac arrhythmia by restoring synchronization to the heart. That appears to be what has occurred in animal studies carried out at MetroHealth.

Under the direction of Rosenbaum, MetroHealth tested the drug in guinea pigs after feeding the animals a solution that made the coronary circulation more acidic, creating conditions that mimic a heart attack.

ZP123 could be ready for clinical trials within a year, said Rosenbaum. Unlike the simulated studies tried in animals, the drug would be tested only in people already in the throes of a heart attack, said Rosenbaum.

Though there have been numerous attempts to treat cardiac arrest with drugs, most of the therapies have failed because not only did they not suppress cardiac arrhythmias, they actually triggered them in some cases.

Rosenbaum, who is now a consultant for Zealand on this particular research venture, believes ZP123 could provide heart patients with a good alternative to ICDs, alleviating the need for surgery and the $20,000 cost associated with ICDs.