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Myocardial bridging in children with hypertrophic cardiomyopathy--a risk factor for sudden death
A T Yetman1, B W McCrindle, C MacDonald
1Department of Pediatrics, Hospital for Sick Children, University of Toronto Faculty of Medicine, Canada.
Insights
Myocardial bridging in children with hypertrophic cardiomyopathy is linked to increased risks of chest pain, cardiac arrest, and worse outcomes. This condition is associated with myocardial ischemia, impacting prognosis.
Area of Science:
- Cardiology
- Pediatric Cardiology
- Cardiovascular Research
Background:
- Myocardial bridging can compress coronary arteries, potentially causing myocardial ischemia.
- The clinical significance of myocardial bridging in pediatric hypertrophic cardiomyopathy (HCM) is not well understood.
- This study investigates the prevalence and effects of myocardial bridging in children with HCM.
Purpose of the Study:
- To determine the prevalence of myocardial bridging in children with hypertrophic cardiomyopathy.
- To assess the clinical effects and prognostic value of myocardial bridging in this patient group.
Main Methods:
- Retrospective review of angiograms from 36 children with HCM.
- Assessment of left anterior descending coronary artery systolic narrowing and diastolic compression due to myocardial bridging.
- Review of clinical data, including symptoms, cardiac events, and exercise test results.
Main Results:
- Myocardial bridging was present in 28% of pediatric HCM patients.
- Patients with bridging showed higher rates of chest pain, cardiac arrest, and ventricular tachycardia.
- Bridging was associated with reduced exercise blood pressure, increased ST depression, shorter exercise duration, and greater QT dispersion.
- Five-year survival free from death or cardiac arrest was significantly lower in patients with bridging (67% vs. 94%).
Conclusions:
- Myocardial bridging is associated with a significantly poorer prognosis in children with hypertrophic cardiomyopathy.
- The findings suggest that myocardial bridging contributes to myocardial ischemia in these patients, exacerbating their condition.
Background:
Myocardial bridging may cause compression of a coronary artery, and it has been suggested that myocardial ischemia may result. The clinical significance and prognostic value of myocardial bridging of the left anterior descending coronary artery in children with hypertrophic cardiomyopathy are unknown. We sought to determine the prevalence and clinical effects of myocardial bridging in children with hypertrophic cardiomyopathy who underwent cardiac catheterization.
Methods:
Angiograms from 36 children with hypertrophic cardiomyopathy were reviewed to determine whether myocardial bridging was present and, if so, to assess the characteristics of systolic narrowing of the left anterior descending coronary artery caused by myocardial bridging and the duration of residual diastolic compression. We also reviewed clinical data on these patients.
Results:
Myocardial bridging was present in 10 (28 percent) of the patients. Compression of the left anterior descending coronary artery persisted for a mean (+/-SD) of 50+/-17 percent of diastole. As compared with patients without bridging, patients with bridging had a greater incidence of chest pain (60 percent vs. 19 percent, P=0.04), cardiac arrest with subsequent resuscitation (50 percent vs. 4 percent, P=0.004), and ventricular tachycardia (80 percent vs. 8 percent, P<0.001). On average, the patients with bridging had a reduction in systolic blood pressure with exercise of 17+/-27 mm Hg, as compared with an elevation of 43+/-31 mm Hg in those without bridging (P<0.001). The patients with bridging also had greater ST-segment depression with exercise (median, 5 vs. 0 mm, P=0.004) and a shorter duration of exercise (mean, 6.6+/-2.4 vs. 9.1+/-1.4 minutes, P=0.008). The degree of dispersion of the QT interval corrected for heart rate on the electrocardiogram was greater in patients with bridging than in those without bridging (104+/-46 vs. 48+/-31 msec, P=0.002). Kaplan-Meier estimates of the proportions of patients who had not died or had cardiac arrest with subsequent resuscitation five years after the diagnosis of hypertrophic cardiomyopathy were 67 percent among patients with bridging and 94 percent among those without bridging (P=0.004).
Conclusions:
Myocardial bridging is associated with a poor outcome in children with hypertrophic cardiomyopathy. Our observations suggest that bridging is associated with myocardial ischemia