TUESDAY, May 5, 2009 (HealthDay News) -- People treated for heart attack who experience abnormal heart rhythms during artery-opening procedures such as angioplasty may be at increased risk of death, a new study suggests.
The finding could challenge current cardiac care guidelines, experts say.
The study focused on patients who had heartbeat abnormalities called ventricular tachycardia or ventricular fibrillation when they underwent what is formally called a percutaneous coronary intervention (PCI) -- such as angioplasty with or without stent placement -- for heart attack.
Patients who experienced these cardiac arrhythmias during the procedure had about triple the odds of dying within 90 days as those whose hearts beat normally, the researchers found.
"Arrhythmias have a significant impact on longer-term survival," concluded study author Dr. Rajendra H. Mehta, an associate consulting professor of medicine at Duke University in Durham, N.C.
His team published the findings in the May 6 issue of the Journal of the American Medical Association.
The study, which included more than 5,700 people treated at 296 centers in 17 countries, produced results that differed considerably from those of a 2004 study, which Mehta also led. That study found no increased risk of death for people with heart arrhythmias during a PCI.
However, the earlier trial "included only lower-risk patients," Mehta noted. "This [newer] study was designed to look at patients at higher risk."
People with more severe heart attacks and less blood flow to the heart were at higher risk of heart rhythm abnormalities during an angioplasty, the study showed.
Another important finding of the study was that "most deaths occur very early in this population," Mehta said. "Most deaths occur in the first 30 days. Other than that, the rates of mortality are similar."
The finding could challenge current cardiac care guidelines. That's because current rules for implanting a defibrillator -- a device that can deliver a shock to correct an abnormal heartbeat -- say that the implant should not be done in the first 30 days after angioplasty/stenting, Mehta said.
However, it's still premature to say that the guideline should be changed, he noted.
"We don't have enough data to say that," Mehta said. "We may be able to challenge the current guidelines in the future if the data holds up, but currently we don't."
Most cardiologists now believe that episodes of abnormal heart rhythm during PCI are not important, he added. The new findings could change that attitude, singling out people who are at higher risk and require closer monitoring, he said.
About 6 percent (329) of the people in the study experienced arrhythmias; 25 before PCI, 180 during and 117 afterward. The 90-day death rate in those that experienced an irregular heartbeat was just over 23 percent, compared to 3.6 percent for those with no heart rhythm abnormalities. The overall threefold increase in risk was calculated by including other risk factors.
The next step is to determine whether specific interventions might improve the outlook in cases where arrhythmias occur, Mehta said. "We are now doing a longer follow-up of another trial, studying one-year mortality to see if any treatments have improved outcomes," he said.
It is already well known that beta blockers can cut the risk for people with heartbeat abnormalities, Mehta said. "Whether other anti-arrhythmics help, we can't say from the current study," he added.
The study is useful because it may help physicians single out people who need the most attention, said study co-author Dr. Judith S. Hochman, a professor of cardiology at New York University, New York City.
"Its helpful to understand the risk in terms of the intensity with which one monitors the patients," she said."
Not everyone who undergoes angioplasty or other PCI will require a stay in an intensive care unit, Hochman noted. "This helps sort out who would be good for one place rather than the other," she said.
And more work is needed before the finding is put to widespread use. "This [finding] should be confirmed in other studies before we change practice," she said.
There's more on ventricular fibrillation at the American Heart Association.