Isolierter intrakardialer echogener Herzfokus: Beurteilung der Assoziation mit Trisomie 21 durch Kombination von Ergebnissen aus einem Praenatalzentrum mit einer Bayes´schen Metaanalyse.

Objective: To investigate the clinical relevance of an isolated echogenic cardiac focus (iECF) as a marker for trisomy 21 using a large second trimester collective including a low risk subgroup. Material and Methods: We retrospectively evaluated 125,211 pregnancies from 2000-2016 and analysed all iECF cases with regard to chromosomal anomalies. It consisted an early second trimester collective from 14+0-17+6 weeks (n=34,791) and a second trimester anomaly scan collective from 18+0-21+6 weeks. Two a priori risk subgroups (high and low risk) of the latter were built based on maternal age and previous screening test results using a cut-off of 1:300. Likelihood ratios (LR) of iECF for the detection of trisomy 21, trisomy 13, trisomy 18 and structural chromosomal anomalies were estimated. Results: In total, 104,001 patients were included. An iECF was found in 4,416 of 102,847 euploid fetuses (4,29%) and in 64 of 557 cases with trisomy 21 (11,49%) giving a positive LR of 2.68 (CI:2.12-3.2). Sensitivity was 11.5% at a false positive rate of 4.29% (CI:4.17-4.42) with p≤0.01%. In the high-and low-risk subgroups the prevalence of iECF was comparable: 5,08% vs. 5.05%. Frequency of trisomy 21 was 0,39%, 98/24,979 vs 0.16%, 69/44,103. LR+ was 3.86 (2,43-5.14) and 2.59 (1.05-4). For both subgroups the association of iECF with trisomy 21 was statistically significant. The prevalence of structural chromosomal anomalies in the second trimester anomaly scan collective was 0,08% (52/68,967), of which 2 showed an iECF. Conclusion: The detection of an iECF at the time of 14+0-21+6 weeks does significantly increase the risk for trisomy 21 as well in the high risk as in the low risk subgroups and does not statistically change the risks for Trisomy 13/18 or structural abnormalities.