Wednesday, January 24, 2018

A simple, reassuring test for heart murmurs in children

It happens all the time to family physicians at well-child visits: we listen to the heart with our stethoscopes, hear a murmur that wasn't documented as being there before, and wonder if it's necessary to obtain an echocardiogram and/or refer the child to a cardiologist. A previous article in American Family Physician by Drs. Jennifer Frank and Kathryn Jacobe listed several "red flags" that make a serious cause more likely:

- Holosystolic or diastolic murmur
- Grade 3 or higher murmur
- Harsh quality
- Abnormal S2
- Maximum murmur intensity at the upper left sternal border
- A systolic click
- Increased intensity when the patient stands

The authors also recommended referral to a pediatric cardiologist if historical findings suggest structural heart disease, if cardiac symptoms are present, or if the family physician is unable to identify a specific innocent (physiologic) murmur. Even though innocent murmurs share several characteristics, some of these are subjective or difficult to distinguish, and the fear of missing a heart disease diagnosis may still lead to unnecessary referrals.

In an important research study published in the November/December issue of Annals of Family Medicine, Dr. Bruno Lefort and colleagues prospectively evaluated 194 consecutive children aged 2 or older referred for heart murmur evaluations at 2 French medical centers to test the hypothesis that a simple, objective clinical test could exclude serious cardiac conditions. 100 children had a murmur that was present when lying down but completely disappeared when they stood up, per the pediatric cardiologists' examinations. Of these children, only two had an abnormal echocardiogram result, and only one required further evaluation and treatment for a non-trivial problem (an atrial septal defect that required percutaneous closure). The authors calculated that the complete disappearance of the heart murmur on standing had a positive predictive value of 98%, specificity of 93%, and sensitivity of 60% for innocent murmurs in children. This "clinical standing test" had superior predictive value compared to features of physiologic murmurs traditionally taught in medical school, such as change in murmur intensity, location, or timing.

The investigators concluded that the complete disappearance of the murmur on standing may be a valuable test to rule out serious heart murmurs in children and prevent unnecessary imaging and referrals. They recommended that a larger study confirm the value of this test and its reproducibility between pediatric cardiologists and primary care physicians (whose assessments were not evaluated in this study).

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A slightly different version of this post first appeared on the AFP Community Blog.

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