The Utility of Echocardiography in Pediatric Patients with Structurally Normal Hearts and Suspected Endocarditis

The Utility of Echocardiography in Pediatric Patients with Structurally Normal Hearts and Suspected Endocarditis.

Kelly P, Hua N, Madriago EJ, Holmes KW, Shaughnessy R, Ronai C.

Pediatr Cardiol. 2020 Jan;41(1):62-68. doi: 10.1007/s00246-019-02222-z. Epub 2019 Oct 31.

PMID: 31673735

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Take Home Points:

  • A single positive blood culture without other major or minor Modified Duke’s Criteria (MDC) and no prior history of congenital heart disease has a positive predictive value of 0 for infectious endocarditis (IE)
  • Two positive cultures without other criteria also has a very low PPV
  • MDC should be used to assess the clinical probability of IE; if low, a TTE is not recommended due to poor diagnostic yield

Commentary from Dr. Jared Hershenson (Greater Washington DC), section editor of Pediatric Cardiology Journal Watch:  While sonographic findings are part of the major criteria for MDC, they are usually meant to supplement clinical judgment when there is a higher pretest probability of IE. The sensitivity and specificity in adults is not great for IE, and the ACC/AHA calls TTE an inadequate screening tool. This study was a retrospective chart review to determine the diagnostic yield of TTE in children with suspected IE and structurally normal hearts and no prior history of IE. 300 patients were included. Charts were reviewed to determine whether patients met any MDC prior to the echocardiogram. Clinical IE was determined if patients were treated with 4-6 weeks of IV antibiotics. Positive TTE findings were defined as mass, abscess, thrombus or new significant valvular regurgitation.

Over the 10 year study period, 10/300 (3.3%) had positive TTE findings. Of those 10 patients, 8 were treated for IE with 2 false positives that the authors detail. Of the 290 with negative TTE, 3 were diagnosed with IE. These were all teenagers with poorer echo images and clinical features strongly suggestive of IE. See tables 3 and 4.  98 patients (33%) had 2 positive blood cultures; 7 were diagnosed with IE, with one likely having a false positive TTE and the other 6 having some MDC. The PPV of 2 positive cultures and no MDC risk factors was 0.071. 46 patients (15.3%) had only 1 positive blood culture. The PPV of 1 positive culture and no additional MDC risk factors was 0. The PPV of those that met MDC prior to TTE was 0.86. See table 5.

There was pretty clear data that those with 1 or 2 positive blood cultures and no other MDC risk factors have a very low likelihood of IE and a positive echo. Misdiagnosis of IE obviously has increased morbidity (need for CVL and antibiotics) and TTE can have false positives. Therefore, use of MDC should be strongly recommended prior to obtaining a TTE. A few caveats/limitations include poor documentation of various vascular and immunologic findings in their chart review. Additionally, while presence of CHD is a risk factor, this study does not address the risk/PPV in this population.