Relation between QT duration and maximal wall thickness in familial hypertrophic cardiomyopathy.
BACKGROUND
QT abnormalities have been reported in left ventricular hypertrophy and hypertrophic cardiomyopathy.


OBJECTIVE
To determine the relation between left ventricular hypertrophy and increased QT interval in familial hypertrophic cardiomyopathy.


METHODS
The QT interval was measured in 206 genotyped adult subjects with familial hypertrophic cardiomyopathy from 15 unrelated families carrying mutations in the beta myosin heavy chain (beta-MHC) gene (five families, n = 68) or the cardiac myosin binding protein C (MyBPC) gene (10 families, n = 138). Subjects were classified as genetically unaffected (controls, n = 112), affected with left ventricular hypertrophy (penetrants, n = 58), or affected without left ventricular hypertrophy (non-penetrants, n = 36).


RESULTS
There was a significant increase in QTmax and QTmin from controls to non-penetrants and penetrants for both the MyBPC group (p < or = 0.001 and p < or = 0.001, respectively) and the beta-MHC group (p < or = 0.001 and p < or = 0.001, respectively). In the MyBPC group, the increase in the QT interval could be explained by increased left ventricular hypertrophy. In the beta-MHC group, non-penetrants had a significantly longer QTmax than controls despite the absence of left ventricular hypertrophy, and a similar QT interval to penetrants despite a lesser degree of left ventricular hypertrophy.


CONCLUSIONS
In familial hypertrophic cardiomyopathy, genetically affected subjects without left ventricular hypertrophy may have a prolonged QT duration, which depends not only on the degree of left ventricular hypertrophy, when present, but also on the causative mutation.
Jouven
X
X
Service de Cardiologie, Hôpital Européen Georges Pompidou, Paris, France. xavier.jouven@hop.egp.ap-hop-paris.fr
Hagege
A
A
Charron
P
P
Carrier
L
L
Dubourg
O
O
Langlard
J M
JM
Aliaga
S
S
Bouhour
J B
JB
Schwartz
K
K
Desnos
M
M
Komajda
M
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D024741:Cardiomyopathy, Hypertrophic, Familial / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005838:Genotype; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000502:physiology; D018995:Myosin Heavy Chains / Q000235:genetics; D015588:Observer Variation
D018995:Myosin Heavy Chains