Relationship of functional mitral regurgitation to new-onset atrial fibrillation in acute myocardial infarction.
OBJECTIVE
The role of factors that increase left atrial pressure or cause acute left atrial dilatation is frequently emphasised in the pathogenesis of atrial fibrillation (AF) in patients with acute myocardial infarction (AMI). This study was designed to test the hypothesis that functional mitral regurgitation (FMR) occurring after AMI may promote AF by producing left atrial volume overload.


METHODS
Intensive care unit of a tertiary care hospital.


METHODS
1920 patients admitted with AMI were studied. Patients with known AF were excluded. FMR was classified using echocardiography into three groups: none; mild FMR and moderate or severe FMR. The relationship between FMR and AF occurring at any time during the hospital course was examined using multivariable logistic regression.


RESULTS
Mild FMR was present in 744 patients (38.8%) and moderate or severe FMR was present in 150 patients (7.8%). AF developed in 51 (5.0%), 83 (11.2%) and 28 (18.7%) patients with no FMR, mild FMR and moderate or severe FMR, respectively (p trend <0.001). In multivariable logistic regression, both mild (odds ratio (OR) 1.6; 95% CI 1.1 to 2.3, p=0.02) and moderate or severe FMR (OR 2.1; 95% CI 1.2 to 3.6, p=0.007) were independent predictors of AF. There was a significant interaction between the left ventricular ejection fraction and FMR (p=0.003) such that mild FMR was predictive of AF only in patients with a reduced (<45%) ejection fraction.


CONCLUSIONS
There is a graded independent association between the severity of FMR and the new onset of AF in patients with AMI.
Bahouth
Fadel
F
Department of Cardiology, Rambam Medical Center, Bat Galim, POB 9602, Haifa 31096, Israel.
Mutlak
Diab
D
Furman
Moran
M
Musallam
Anees
A
Hammerman
Haim
H
Lessick
Jonathan
J
Dabbah
Saleem
S
Reisner
Shimon
S
Agmon
Yoram
Y
Aronson
Doron
D
D001281:Atrial Fibrillation / Q000209:etiology* / Q000401:mortality; D005260:Female; D006333:Heart Failure / Q000209:etiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000150:complications* / Q000401:mortality; D009203:Myocardial Infarction / Q000150:complications* / Q000401:mortality; D011446:Prospective Studies; D012307:Risk Factors; D016896:Treatment Outcome