Three Part Question
In [children with an asymptomatic heart murmur] does a [chest x ray and/or ECG examination] assist in [the diagnosis or exclusion of congenital heart disease]?
A six-month-old infant is referred by the GP to the general paediatric clinic with an asymptomatic heart murmur. A careful history does not reveal any symptoms of heart disease. On examination there is a soft systolic heart murmur but is otherwise normal. You suspect that the child has an innocent heart murmur but are not 100% sure. In this case will a Chest X-ray and ECG add to your clinical evaluation?
Secondary sources, Primary sources: Medline 1966-October week 2 2001.
(Heart murmurs OR (heart murmur$ OR cardiac murmur$).tw.) AND (Electrocardiography OR ECG.mp) AND (radiography, thoracic.mp. OR chest xray.mp, OR chest x-ray.mp OR chest radiograph.mp) AND (Heart defects, Congenital/ OR congenital heart disease.mp OR heart defects congenital/ra) LIMIT to children <0-18years> AND English
132 articles found, 10 articles relevant to clinical question. Four excluded due to poor quality. Serendipity: 1 article
|Author, date and country
||Study type (level of evidence)
|Smythe et al,|
|161 children aged 1 month-17 years with asymptomatic heart murmur referred to paediatric cardiologist||Prospective cohort (Level 2b) Reference standard was echocardiography||Correct identification of a pathologic heart murmur after clinical evaluation & then ECG||ECG led to no change in diagnosis|
Specificity 95 %
NPV 98 %
|Prevalence of heart murmur: up to 50% of paediatric population
Paediatric cardiologist evaluating patients & ECG
Independent reference standard ECHO applied to all but NOT blinded|
|Birkebaek et al,|
|100 children aged 1 month-15 years with asymptomatic heart murmur referred to general paediatrician||Prospective cohort (Level 2b) Reference standard was echocardiography||Correct diagnosis of heart murmur after clinical evaluation then ECG & CXR||3 abnormal ECG's all evaluated to have heart disease after clinical evaluation|
|Independent reference standard ECHO applied blindly to all patients
No prevalence for heart murmurs given|
|Birkebaek et al,|
|100 children aged 1 month-15 years with asymptomatic heart murmur referred to general paediatrician||Prospective cohort (Level 2b)||Accuracy of chest X-ray evaluation by paediatric radiologists||Mean intra-observer k value: All films= 0.452|
Mean inter-observer k value:
All films= 0.282
|Same cohort of patients as in Birkebaek et al (1995)
Interpretation of chest X-ray by a paediatric radiologist is only poorly to moderately reproducible|
|Temmerman et al,|
|284 children referred to paediatric cardiologist for cardiology evaluation aged 0.5-17 years (nearly all heart murmurs)||Prospective cohort (Level 3b) Reference standard was echocardiography||Correct diagnosis of a heart murmur after clinical evaluation & then CXR||CXR led to diagnosis of heart disease in 2.8% of patients diagnosed with normal heart after primary evaluation|
In 2.8% of patients with a diagnosis of heart disease after 1st evaluation CXR led to a change in diagnosis to no heart disease
|No prevalence given for heart murmurs
Not specified asymptomatic heart murmurs
CXR not performed in all referred patients
Reference standard ECHO not applied to all patients|
|Swenson et al,|
|106 children aged 1 month-14 years with heart murmur or chest pain, referred to paediatric cardiologist||Prospective cohort (Level 4) Reference standard was echocardiography||Correct diagnosis of heart murmur after clinical evaluation then ECG & CXR||4 patients evaluated normal heart, diagnosed heart disease on basis of ECG & CXR|
3 patients ECG & CXR misled diagnosis
|ECHO only applied to 45/106 patients
Patients included with chest pain ?skewed results as higher proportion of abnormal ECG's than previous studies|
|Rajakumar et al,|
|128 children aged 1 month-18 years referred to paediatric cardiologist with a heart murmur||Prospective cohort study (Level 4) Reference standard was echocardiography||Correct diagnosis of heart murmur by general paediatrician compared to paediatric cardiologist after clinical evaluation then ECG & CXR||General paediatricians clinical evaluation alone /after ECG & CXR|
Paediatric cardiologist clinical evaluation alone /after ECG & CXR
General paediatrician: ECG & CXR helpful in 2 cases & misleading in 3 cases
Paediatric cardiologists;ECG & CXR misleading in 9 cases & helpful in 5 cases
|Reference standard was applied blindly to all 128 patients but 28 patients were excluded from the study (as no ECHO was performed as deemed no heart disease by Paed. Cardiologists)|
Paediatric cardiologists have undertaken most of the research investigating the assessment of the child with a heart murmur, with and without ECG and chest x ray examination. However the Birkebaek et al study evaluates the general paediatricians' assessment of a heart murmur and the Rajakumar et al study compared academic general paediatricians and paediatric cardiologists. I could find no studies comparing trainees and consultants.
In the study by Rajakumar et al, general paediatricians and paediatric cardiologists each evaluated the patient referred with a heart murmur (blind to the others' assessment) and classified them innocent, possibly pathologic or pathologic murmur. They then had a chest x ray and ECG examination and were reclassified. An echocardiogram was then performed, which gave them a definitive diagnosis. The paediatricians classified more innocent murmurs as pathologic and the cardiologists identified more innocent murmurs correctly. After ECG and chest x ray examination paediatricians revised 5 diagnoses, 3 incorrectly. That is for the vast majority ECG and chest x ray examination did not help in the diagnosis, and in those cases where it was thought helpful it was often misleading.
The likelihood ratio of a test, calculated from the sensitivity and specificity, gives an estimate of increased probability of correctly identify a condition (positive likelihood ratio) or excluding a diagnosis (negative likelihood ratio) when using the diagnostic tool in question. A reasonable pretest probability is assumed and then, using Fagan's likelihood ratio nomogram, the post-test probability is calculated (see Archimedes in January 2003). For example, if the pretest probability of a pathological heart murmur was 5%, an abnormal chest x ray examination (with a likelihood ratio of 2.36 (Birkebaek et al)) would make the post-test probability of cardiac pathology only about 10%. It was only possible to calculate likelihood ratios for chest x ray examination in one paper and the other likelihood ratios were calculated for clinical evaluation. Interestingly in the Rajakumar study the likelihood ratios after ECG and chest x ray examination were very similar to those after clinical evaluation - that is, little was added by doing these tests.
Birkebaek et al evaluated the accuracy of the paediatric radiologists in their interpretation of chest x rays of children with heart murmurs. This paper is relevant as most paediatricians will rely on the report from the radiologist. The 6 radiologists were each asked to report on all the films blind to the result of the echocardiogram, and six months later the chest x rays were re-evaluated by the same radiologists. The results showed only poor to moderate agreement between radiologists, and more surprisingly poor agreement when the same radiologist reviewed the films 6 months later.
Overall, it appears from the above research that ECG and chest x ray examination add little to the clinical evaluation of the child with an asymptomatic heart murmur. Concerns about a pathological cause after clinical examination should prompt a referral to a paediatric cardiologist for further assessment.
Clinical Bottom Line
ECG rarely adds to clinical evaluation of an asymptomatic heart murmur. It rarely leads to a change in diagnosis.
Chest x ray examination is often misleading in the evaluation of an asymptomatic heart murmur and interpretation is only poorly to moderately reproducible.
- Smythe JF, Teixeira OH, Vlad P et al. Initial evaluation of heart murmurs: are laboratory tests necessary? Pediatrics 1990;86(4):497-500.
- Birkebaek NH, HAnsen LK, Oxhoj H. Diagnostic value of chest radiography and electrocardiography in the evaluation of asymptomatic children with a cardiac murmur. Acta Paediatr 1995;84(12):1379-81.
- Birkebaek NH, Hansen LK, Elle B, et al. Chest roentgenogram in the evaluation of heart defects in asymptomatic infants and children with a cardiac murmur: reproducibility and accuracy. Pediatrics 1999;103:e15.
- Temmerman AM, Mooyaart EL, Taverne PP. The value of the routine chest roentgenogram in the cardiological evaluation of infants and children. A prospective study. Eur J Pediatr 1991;150(9):623-6.
- Swenson JM, Fischer JM, Miller SA. Are chest radiographs and electrocardiograms still valuable in evaluating new pediatric patients with heart murmurs or chest pain? Pediatrics 1997;99:1-3.
- Rajakumar K, Weisse M, Rosas A et al. Comparative study of clinical evaluation of heart murmurs by general pediatricians and pediatric cardiologists. Clin Pediatr (Phila) 1999;38(9):511-8.