Early cardiac morphologic and functional changes in neurofibromatosis type 1 hypertensives: an echocardiographic and tissue Doppler study

Background: Hypertension is frequently associated with neurofibromatosis type 1 (NF1), a common inherited disease that limits life expectancy. No data are available on cardiac damage in NF1 patients with hypertension. We evaluated cardiac function in NF1 patients with hypertension diagnosed by 24-h ambulatory blood pressure monitoring (ABPM), compared with normal children. Methods: We studied 73 NF1 patients (41 boys; mean age 12 years) and 30 normal children comparable for age and sex, using standard 2D echocardiography, standard Doppler and Doppler tissue imaging (DTI). Twelve patients (16%) showed 24-h systolic blood pressure (SBP) or 24-h diastolic blood pressure (DBP) >95th percentile for age and sex. We divided the NF1 group into two subgroups: group A, patients with 24-h SBP and DBP ≤95th percentile for age and sex, and group B, patients with 24-h SBP or DBP >95th percentile for age and sex. Results: Group B presented a thicker end-diastolic interventricular septum (p<0.0001), posterior wall (p=0.02), LVMI (p<0.001) and relative wall thickness (p<0.03) than group A and controls. Left atrial dimension in group B was also significantly larger. Examination by standard Doppler showed a deceleration and isovolumic relaxation time significantly prolonged in group B. DTI parameters were significantly higher in NF1 patients than controls. In group B, myocardial early diastolic (Em) and systolic (Sm) velocities were significantly lower than group A. Myocardial early/late diastolic ratio (Em/Am) in NF1 patients was lower than controls and 19% of group A and 20% of group B showed an Em/Am ratio <1. No healthy subjects presented an Em/Am ratio <1. Conclusions: We demonstrated early cardiac morphologic and functional changes in young NF1 patients with hypertension. Because DTI directly studies cardiac muscle, it can detect changes induced by hypertension as well as those independent of blood pressure.