Methods and Results
In the study, 611 patients were included after CABG. All patients had
echocardiograms performed preoperatively and LA functional measurements
were assessed. These measurements were LA maximum volume index (LAVmax),
LA minimum volume index (LAVmin) and LA emptying fraction (LAEF). The
endpoint was AF occurring >14 days after surgery.
During the follow-up period of a median of 3.7 years, 52 (9%) developed
AF. The mean age was 67 years, 84% were male and the average left
ventricle ejection fraction was 50 %. No differences were observed
between the patients developing AF and those who did not develop AF. No
functional LA measurements were significant predictors of AF in the
whole CABG population. However, in patients with normal-sized LA (n=532,
events: 49), both LAEF and LAVmin were univariable predictors of AF.
When the functional measurements were adjusted for the
CHADS2 score, both LAVmin (HR=1.07 (1.01-1.13), p=0.014
) and LAEF (HR: 1.02 (1.00-1.03, p= 0.023)), remained significant
predictors.
ConclusionNo echocardiographic measurements were significant predictors of AF
after CABG. In patients with a normal LA size, LAVmin as well as LAEF
were significant predictors of AF.
Keywords: atrial fibrillation; cardiac surgery; left atrium;
echocardiography
Introduction
Coronary artery bypass grafting (CABG) is the most performed major
cardiovascular surgery procedure in the US, constituting half of all
major cardiovascular
procedures (1). The
most common postoperative arrhythmia following CABG is atrial
fibrillation (AF) (2)
(3). AF is also the
most common cardiac arrhythmia overall with increased risk of stroke
(4). Hence, being able
to identify patients at risk of AF is key to prescribing anticoagulants
and preventing ischemic strokes. With correct screening, the risk of
post-operative complications can be reduced as the treatment and
monitoring of the patient can be individually tailored. Currently,
congestive heart failure, hypertension, age >75 years,
diabetes, and previous stroke/transient ischemic attack
(CHADS2) are used to determine the appropriate
anticoagulant treatment for patients to prevent strokes. This scoring
system is associated to the development of post-operative AF (POAF) and
is also used to predict
AF (5). However, an
improved model for predicting AF in patients with a CABG may decrease
mortality due to a decrease in the number of patients experiencing
stroke.
Patients are routinely examined before CABG with an echocardiogram to
identify valvular disease and to evaluate the systolic function.
Currently, the most widely used echocardiographic measurement in the
clinic for predicting AF is the maximal volume of the left atrium
(LAVmax) (6). Several
studies have found that functional measurements of the left atrium (LA),
such as the LA emptying fraction (LAEF) and the LA minimum volume index
(LAVmin), are useful in predicting AF (7,8). Since it seems that the LA
functional measures can play a role in predicting AF, we hypothesized
that: 1. The LA
functional measurements would be better predictors than LAVmax for AF
following CABG. Furthermore, we hypothesized that: 2. LA functional
measurements would be significant predictors of AF even in patients with
a normal LA size.