Objectives. We sought to determine clinical, angiographic, and echocardiogr
aphic predictors of survival in children with isolated hypertrophic cardiom
yopathy (HCM) in a large pediatric centre.
Background. Sudden death is a catastrophic outcome of HCM in childhood but
has been difficult to predict. Current therapies might provide for improved
outcome if factors identifying high risk can be identified.
Methods. Records of 99 patients diagnosed with HCM from 1958 to 1997 at <18
yr were reviewed for clinical, angiographic (n = 62) and echocardiographic
(n = 83) predictors of survival outcome. The effects of clinical character
istics on sudden death (including resuscitated sudden death) were individua
lly tested in Cox's proportionate hazard modeling.
Results. Seventy-one subjects were male. Median age at diagnosis was 5.0 yr
with a medical follow-up interval of 4.8 yr. Thirty-seven of 97 patients h
ad a family history of HCM. Ambulatory electrocardiograms (ECG) in 78 patie
nts demonstrated supraventricular tachycardia in 16 and ventricular tachyca
rdia in 21. Death or resuscitated sudden death occurred in 18 patients. Sud
den death rate was 2.7%/yr after age 8 yr. Cox's proportionate survival mod
eling revealed increased corrected QT interval (QTc) dispersion on ECG (rel
ative risk [RR] 1.61 per 20 ms increment, p < 0.0003), ventricular tachycar
dia (VT) on ambulatory ECG (RR 3.75, p < 0.006) and myocardial bridging of
the LAD coronary (RR 12.0, p < 0.003) to be associated with reduced time to
death or resuscitated sudden death.
Conclusions. Detailed assessment of ECGs, ambulatory ECGs, and coronary ang
iography can assist in identifying which children with HCM are at risk for
sudden death. (J Am Coll Cardiol 1998;32:1943-50) (C) 1998 by the American
College of Cardiology.