Monitoring Beta-Blocker Therapy in Children with Exercise-Induced Intraventricular Gradients Using Exercise Stress Echocardiography

Background: Treadmill exercise stress echocardiography (ESE) is both fea-sible and safe in the pediatric population. Although regional wall motion abnormalities (RWMA) have limited diagnostic utility, Doppler studies frequently demonstrate sig-nificant intraventricular pressure gradients (IVPGs) during exercise. These IVPGs, ob-served in 39% of 258 previously studied children, are absent at rest. Their detection provides valuable insight into exercise-related symptoms and abnormal findings on resting or stress electrocardiograms (ECGs). Purpose: To evaluate the effect of β-blocker therapy on the occurrence of intraventricular pressure gradients (IVPGs) in children presenting with symptoms or abnormal findings on resting or stress electrocardiograms (ECGs). Methods: Exercise stress echocardiography (ESE) was repeated in 66 of the 101 children who had developed intraventricular pressure gradients (IVPGs) during the initial assessment. All participants had normal resting echocardiograms and underwent follow-up evaluation while receiving β-blocker therapy. The study cohort included 15 females (23%) with a mean age of 14.6 ± 1.7 years (range: 11–17 years). Comprehensive two-dimensional and Doppler echocardiographic assessments were performed at baseline and during β-blocker treatment. Results: During the initial ESE, the mean in-traventricular pressure gradient (IVPG) was 105 ± 38 mmHg. Under β-blocker therapy, 37 children no longer developed IVPGs, while in the remaining 29 children, the IVPG was significantly reduced to a mean of 58 ± 32 mmHg (p < 0.0001). The mean heart rate at peak exercise decreased from 178 ± 15 bpm at baseline to 157 ± 9 bpm during the repeat ESE under β-blocker treatment (p < 0.0001). Clinical symptoms were reproduced in 47 children during the initial ESE but occurred in only 7 children during treatment (p < 0.0001). Conclusions: In children presenting with symptoms, abnormal resting or stress ECG findings, and exertional intraventricular pressure gradients (IVPGs), oral β-blocker therapy either prevented the occurrence of IVPGs or significantly reduced their severity. These hemodynamic improvements were associated with the resolution of clinical symptoms in 85% of the symptomatic cohort.