ORLANDO — Development of new-onset atrial fibrillation soon after cardiac surgery presents a sharply increased risk for also having atrial fibrillation several years later, as well as significantly worse long-term survival, according to a study of more than 500 patients.
“Aggressive preventive measures should be applied, especially for patients undergoing cardiac surgery who are at high risk for postoperative atrial fibrillation,” Dr. Rowlens M. Melduni said at the annual scientific sessions of the American Heart Association.
“Atrial fibrillation is a symptom, not a disease. It's a marker of underlying cardiovascular disease,” said Dr. Melduni, a cardiologist at the Mayo Clinic in Rochester, Minn.
To examine the long-term consequences of early AF after cardiac surgery, Dr. Melduni and his associates studied 534 patients from Olmsted County, Minn. The patients, who had no history of AF prior to surgery, underwent coronary bypass surgery, valve surgery, or both between January 2000 and December 2005. Their average age was 66 years, and 70% were men. During the first 30 days after surgery, 37% developed AF, an incidence rate consistent with several prior reports.
During follow-up, which lasted an average of 4 years, the cumulative occurrence of late AF—defined as episodes occurring more than 30 days following surgery—was 51% in patients who had early AF after cardiac surgery and 13% in patients who did not, a significant difference. The average time from surgery to the appearance of late AF was 2.5 years.
In a multivariate analysis, independent risk factors for developing late AF were having early AF after cardiac surgery, which boosted the risk fivefold; undergoing combined bypass and valve surgery, which raised the risk nearly threefold; and developing postoperative renal dysfunction with a serum creatinine level greater than 2 mg/dL, which doubled the risk. This model adjusted for other potential variables such as age, gender, and treatment with a beta-blocker at hospital discharge.
During follow-up, the cumulative survival rate was 60% in patients who had early AF and 78% in those without early AF, a significant difference.
The duration of early AF was also an independent determinant of long-term risk. Patients whose early AF persisted for 3 or more days had twice the risk for late AF as did those with early AF lasting less than 3 days, Dr. Melduni said.
Results from a second study presented by Dr. Melduni in a poster at the meeting documented that patients who developed early postoperative AF often had high left ventricular end diastolic pressure.
Disclosures: None.
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Source Elsevier Global Medical Newswww.nejm.org