Diastolic dysfunction predisposes to atrial fibrillation after cardiac surgery
MedWire News: US researchers have found that left ventricular (LV) diastolic dysfunction is an important mechanism underlying the initiation of postoperative atrial fibrillation (POAF).
Pre-operative assessment of diastolic function could therefore be used to identify high-risk patients who may benefit from prophylactic treatment, and provide useful prognostic information for individual patients, say Rowlens Melduni (Mayo Clinic, Rochester, Minnesota, USA) and co-authors.
AF is a common complication after surgery, and is a major cause of morbidity and mortality, the researchers explain in the Journal of the American College of Cardiology. To investigate the mechanism underlying its development, they conducted a study in 351 patients from Olmstead County in Minnesota.
All patients had pre-operative sinus rhythm and underwent complete LV diastolic function assessment before coronary artery bypass graft and/or valve surgery between 2000 and 2005. Patients with a history of AF, a pacemaker, mitral stenosis, or congenital heart disease were excluded from the study.
The researchers classified patients by diastolic function grade (DFG) ranging from 0 to 3, where normal function was graded 0, and successive levels of dysfunction were graded 1 (impaired relaxation), 2 (pseudonormal), and 3 (reversible or fixed restrictive).
They found that POAF, defined as any episode of AF within 30 days of surgery, occurred in 135 (38.5%) patients. These patients were older (mean age 72.5 years vs 63.1 years, p<0.001) and more likely to have abnormal diastolic function than those who did not have POAF.
The incidence of POAF increased exponentially with DFG severity. Indeed, 5.1% of patients with normal diastolic function had POAF compared with 34.6% of those with DFG 1, 58.2% of those with DFG 2, and 70.8% of those with DFG 3.
Multivariate analysis revealed that diastolic dysfunction at all three DFGs independently predicted POAF, along with age and BMI.
Patients with DFG 1 had a five-fold increased odds of POAF, those with DFG 2 a 10-fold increased risk, and those with DFG 3 a nearly 30-fold increased odds of POAF.
"Diastolic dysfunction is a powerful predisposing substrate for the initiation of POAF after cardiac surgery," say the authors.
Melduni et al conclude: "Further studies are needed to show whether reduction of LV filling pressure before cardiac surgery is correlated with a consequent reduction in the risk for POAF."
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By Piriya Mahendra