But for many patients, the effects of the treatment are only temporary; anywhere from one-quarter to one-half of patients relapse within a month of a successful procedure, and 70 percent to 90 percent experience atrial fibrillation again within a year.
And the treatment can be an uncomfortable one. Dr. David Haines, chief of cardiovascular medicine at Beaumont Hospital in Royal Oak, Mich., notes that the electric shock Cheney received through his chest is "the same shock as a person in cardiac arrest gets. A person in atrial fibrillation gets it to restore normal electrical activity."
Cardioversion carries risks of its own, though they are slight. Doctors likely treated Cheney with anticoagulants before the procedure — if he was not on them already — to lessen the chances that the procedure would have dislodged clots, which could have then travel through the bloodstream and led to stroke. Doctors likely also performed imaging tests of his heart to ensure that no clots were present.
"We know that individuals with atrial fibrillation are predisposed to clots and stroke," Zipes says, adding that doctors likely looked to anticoagulants, such as coumadin, to minimize these risks. The other potential problem, Zipes notes, is "the fast heart rate associated with atrial fibrillation.
"This is even more important to patients with defibrillators," he says. "Shocks can be delivered inappropriately because of the increased heart rate associated with atrial fibrillation."
Zipes says this increased heart rate is usually treated with drugs intended to slow the patient's heart rate. But he says that, more important than the immediate consequences, are the implications with regard to Cheney's overall heart health.
"The fact that he came in with a lingering cough, apparently from a cold, certainly could, instead, be a lingering cough from progressive heart failure," Zipes says.
The ABC News Medical Unit contributed to this report.