Heart murmur that resolves when a child moves from a supine to a standing position can reliably rule out pathologic heart murmurs in pediatric patients, a study found. Implementing this low-cost clinical assessment could avoid unnecessary cardiologist referrals and anxiety in parents and children, the researchers write in Annals of Family Medicine.

Children who had a heart murmur while lying supine completely disappeared when they stood up, only 2 proved to have a pathologic murmur caused by a cardiac abnormality. The complete disappearance of an isolated heart murmur on standing exclude a pathologic cardiac murmur and avoid referral to a cardiologist.

Heart murmur affects an estimated 65% to 80% of school children, the authors note, and distinguishing between innocent (i.e., physiologic) heart murmurs and their pathologic (i.e., organic) counterparts can be challenging in routine practice, often prompting costly but unnecessary further tests.

Clinicians auscultated patients' heart sounds in both supine and standing positions, and patients then underwent echocardiography. Children with heart murmurs were on average 6 to 7 years of age, and a majority were boys.

The study identified 30 children with pathologic heart murmurs as determined by echocardiographic abnormalities. Pathologic heart murmurs persisted on standing in 93% of patients and decreased in intensity in 43%, while physiologic murmurs persisted on standing in 40% and decreased in intensity in 80%.

The complete disappearance of the heart murmur in the standing position excluded pathologic heart disease, with a high positive predictive value of 98% (95% confidence interval [CI], 93% – 100%) and a specificity of 93% (95% CI, 78% – 99%). Sensitivity was considerably lower at 60% (95% CI, 52% – 67%).

Dr Lefort and co-authors said that their findings support the need for a basic clinical tool to help primary care physicians rule out underlying cardiac disease in children with heart murmurs.

Disappearance of a heart murmur on standing is a reliable clinical tool for ruling out pathologic heart murmurs in children aged 2 years and older. This basic clinical assessment would avoid many unnecessary referrals to cardiologists.