Right ventricular MR abnormalities in myotonic dystrophy and relationship with intracardiac electrophysiologic test findings: initial results.
OBJECTIVE
To prospectively determine whether a relationship exists between magnetic resonance (MR) imaging abnormalities of the right ventricle (RV) and intracardiac electrophysiologic (EP) test results in patients with myotonic dystrophy.


METHODS
Conventional T1-weighted single-shot black-blood fast spin-echo and gradient-echo MR imaging of the heart was prospectively performed in 32 patients with myotonic dystrophy who required EP testing. Patients were divided into two groups according to EP test results: (a) inducible (n = 15), indicating inducible ventricular tachyarrhythmias, and (b) noninducible (n = 17). Morphologic and functional MR data were analyzed by two independent investigators. Nonparametric statistical methods and kappa statistics were used.


RESULTS
No morphologic or functional abnormalities of the RV wall were observed in noninducible patients. Increased signal intensity of the RV wall, indicative of fatty replacement, was identified in 13 inducible patients. Myocardial thinning of the RV was observed in six inducible patients. An overlap of morphologically abnormal areas and areas of hypo- or dyskinesis were present in 11 inducible patients. RV outflow tract diameter was larger and RV ejection fraction was smaller in inducible patients than in noninducible patients, although differences were not significant. Interobserver agreement for MR findings was good (increased signal intensity: kappa = 0.87, P >.30 [pairwise Wilcoxon signed rank test]; myocardial thinning: kappa = 0.87, P >.30; hypo- or dyskinesis: kappa = 1.00, P >.99). There was a strong relationship between MR abnormalities and inducibility during EP testing (increased signal intensity, P <.001; myocardial thinning, P <.01; hypo- or dyskinesis, P <.01).


CONCLUSIONS
The relationship between MR morphologic and functional RV abnormalities and EP testing suggests potential for the use of MR imaging as a noninvasive method to estimate the individual risk of arrhythmia in patients with myotonic dystrophy.
Vignaux
Olivier
O
Department of Radiology, Université René Descartes, Hôpital Cochin, 27 rue du Fg Saint Jacques, 75014 Paris, France. olivier.lignaux@cch.ap-hop-paris,fr
Lazarus
Arnaud
A
Varin
Jean
J
Coste
Joel
J
Carlier
Pierre
P
Argaud
Christophe
C
Laforet
Pierre
P
Weber
Simon
S
Legmann
Paul
P
Duboc
Denis
D
D000328:Adult; D000368:Aged; D002304:Cardiac Pacing, Artificial; D004452:Echocardiography; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000503:physiopathology*; D011446:Prospective Studies; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis*