Research may help make atrial fibrillation easier to treat.
"The results of this trial, with an 80 percent ablation success rate after a single procedure, are very gratifying," says study author Kalyanam Shivkumar, MD, PhD, director of the UCLA Cardiac Arrhythmia Center and a professor of medicine and radiological sciences at UCLA. "This is the dawn of a new phase of managing this common arrhythmia that is mechanism-based."
The nature of AFib. AFib is the most common type of arrhythmia, an abnormality of the heart's rate or rhythm. It's caused when the usually synchronized electrical signals in the heart--those that help the heart pump blood strongly and efficiently--stop working correctly in the atria, the heart's upper chambers. Blood doesn't circulate completely through these quivering chambers, and the result is a pooling of blood that can result in a blood clot forming. That blood clot can eventually make its way to the brain and cause a stroke.
AFib is often initially treated with antiarrhythmic drugs, such as amiodarone (Cordarone, Pacerone), bepridil hydrochloride (Vascor), or disopyramide (Norpace). If those medications fail to restore and maintain a healthy rhythm, the next option for patients could be catheter ablation, in which a metal-tipped catheter is threaded through the body from a vein in the groin up to the heart. The tip uses heat to destroy the tiny area of the heart producing the arrhythmia.
AFib episodes can occur frequently in some patients and only occasionally in others. It's a difficult condition to predict and manage. Even after traditional ablation procedures, AFib episodes can return weeks, months, or even years later.
Treating AFib. Accurately finding and ablating the exact source of the arrhythmia can be a challenge. The new research should help cardiologists find their targets in the heart a little more easily. The CONFIRM study examined 107 patients with AFib, who had been referred for a non-surgical catheter ablation procedure.
In one group of patients, the team used the new technique to help perform very small, precise ablations--called focal impulse and rotor modulation, or FIRM--that were aimed directly at the fundamental source of the arrhythmia: the tiny electrical disturbances in the heart called focal beats or "rotors." Researchers likened the rotors to the "eye of a storm" because the study showed them to cause chaos in the heart's electrical system.
The new procedure shut down or at least slowed significantly AFib in 86 percent of patients in an average of just 2.5 minutes. By comparison, conventional catheter procedures were performed in a second group of patients. Since this approach is less targeted, it involved hours of treatment over larger regions in the heart and often did not effectively treat the AFib.
"We are very excited by this trial, which for the first time shows that atrial fibrillation is maintained by small electrical hotspots, where brief FIRM guided ablation can shut down the arrhythmia and bring the heart back to a normal rhythm after only minutes of ablation," said lead author Sanjiv Narayan, MD, a professor of medicine at UC San Diego, a visiting professor at the UCLA Cardiac Arrhythmia Center, and director of electrophysiology at the San Diego Veterans Affairs Medical Center.
To track outcomes, patients received an implanted ECG monitor that very accurately assessed their heart rhythms over time. The researchers found that after two years, the FIRM-guided group had an 82.4 percent freedom from AFib episodes, compared with only 44.9 percent freedom in the group that received standard therapy.
The new targeted method demonstrated an 86 percent improvement over the conventional method.
WHAT YOU CAN DO
* Report episodes of heart palpitations or feelings of an irregular heartbeat to your doctor as these could be signs of undiagnosed atrial fibrillation.
* Limit or avoid alcohol and stimulants such as caffeine if you have already been diagnosed with heart disease or with heart risk factors, such as hypertension and diabetes.
* Follow your doctor's advice on life-style changes and medications, such as beta blockers or calcium channel blockers, if you have been diagnosed with atrial fibrillation and wish to reduce your risk of arrhythmic episodes.
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|Date:||Sep 1, 2012|
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