Electrical remodelling of the left and right atria due to rheumatic mitral stenosis.
OBJECTIVE
To characterize the atrial remodelling in mitral stenosis (MS).


RESULTS
Twenty-four patients with severe MS undergoing commissurotomy and 24 controls were studied. Electrophysiological evaluation was performed in 12 patients in each group by positioning multi-electrode catheters in both atria to determine the following: effective refractory period (ERP) at 10 sites at 600 and 450 ms; conduction time; conduction delay at the crista terminalis (CT); and vulnerability for atrial fibrillation (AF). P-wave duration (PWD) was determined on the surface ECG. In the remaining 12 patients in each group, electroanatomic maps of both atria were created to determine conduction velocity and identify regions of low voltage and electrical silence. Patients with MS had larger left atria (LA) (P < 0.0001); prolonged PWD (P = 0.0007); prolonged ERP in both LA (P < 0.0001) and right atria (RA) (P < 0.0001); reduced conduction velocity in the LA (P = 0.009) and RA (P < 0.0001); greater number (P < 0.0001) and duration (P< 0.0001) of bipoles along the CT with delayed conduction; lower atrial voltage in the LA (P < 0.0001) and RA (P < 0.0001); and more frequent electrical scar (P = 0.001) compared with controls. Five of twelve with MS and none of the controls developed AF with extra-stimulus (P = 0.02).


CONCLUSIONS
Atrial remodelling in MS is characterized by LA enlargement, loss of myocardium, and scarring associated with widespread and site-specific conduction abnormalities and no change or an increase in ERP. These abnormalities were associated with a heightened inducibility of AF.
John
Bobby
B
Cardiovascular Research Center, Department of Cardiology, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia.
Stiles
Martin K
MK
Kuklik
Pawel
P
Chandy
Sunil T
ST
Young
Glenn D
GD
Mackenzie
Lorraine
L
Szumowski
Lukasz
L
Joseph
George
G
Jose
Jacob
J
Worthley
Stephen G
SG
Kalman
Jonathan M
JM
Sanders
Prashanthan
P
D000293:Adolescent; D000328:Adult; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D016275:Atrial Function / Q000502:physiology*; D017115:Catheter Ablation / Q000379:methods*; D004553:Electric Conductivity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008946:Mitral Valve Stenosis / Q000503:physiopathology / Q000628:therapy*; D012032:Refractory Period, Electrophysiological; D016896:Treatment Outcome