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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]?

Clinical Scenario

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?

Search Strategy

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

Search Outcome

132 articles found, 10 articles relevant to clinical question. Four excluded due to poor quality. Serendipity: 1 article

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Smythe et al, 1990	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 Clinical evaluation: Sensitivity 96% Specificity 95 % PPV 88% NPV 98 % LR +=19.2 LR -=0.04	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, 1995,	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 CXR: Sensitivity= 43% Specificity= 82% PPV=42% NPV= 83% LR+=2.36 LR-=0.70	Independent reference standard ECHO applied blindly to all patients No prevalence for heart murmurs given
Birkebaek et al, 1999,	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 Normal films=0.320 Abnormal films=0.595 Mean inter-observer k value: All films= 0.282 Normal films=0.106 Abnormal films=0.531	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, 1991,	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, 1997	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, 1999	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 Sensitivity=79%/82% Specificity=55%/54% PPV=39%/39% NPV=88%/89% LR+=1.76/1.78 LR-=0.38/0.33 Paediatric cardiologist clinical evaluation alone /after ECG & CXR Sensitivity=85%/88% Specificity=77%/70% PPV=57%/51% NPV=93%/94% LR+=3.7/2.9 LR-=0.19/0.17 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)

Comment(s)

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.

References

1. Smythe JF, Teixeira OH, Vlad P et al. Initial evaluation of heart murmurs: are laboratory tests necessary? Pediatrics 1990;86(4):497-500.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.