Fetal cardiac parameters for prediction of twin-to-twin transfusion syndrome.

OBJECTIVES: To assess myocardial performance index measured by conventional Doppler (MPI) and by tissue Doppler imaging (MPI') at 18 weeks' gestation in monochorionic diamniotic twins for the prediction of twin-to-twin transfusion syndrome (TTTS).

METHODS: This was a single-center observational study of 100 uncomplicated monochorionic diamniotic twin pregnancies attending the twin pregnancy clinic at the University Hospital Spedali Civili of Brescia from 2009 to 2012. MPI and MPI' were obtained from the left (LV) and right (RV) ventricles of each twin at around 18 weeks of gestation (range, 17 + 1 to 19 + 4 weeks) and fortnightly thereafter. Cases which later developed TTTS formed the study group, and the remaining controls were subdivided into those continuing as uncomplicated pregnancies and those which later developed selective intrauterine growth restriction (sIUGR). Data were analyzed by receiver-operating characteristics curve analysis and univariate and multivariable logistic regression.

RESULTS: Of the 100 pregnancies, 88 were controls (84 uncomplicated and four developed sIUGR) and 12 developed TTTS. RV-MPI and LV-MPI, and LV-MPI' were significantly higher in future TTTS recipients than in controls, while RV-MPI' was significantly lower in donors. RV-MPI and LV-MPI and LV-MPI' were found to be predictive indicators in pregnancies that had not yet developed TTTS. Their negative predictive values were > 90%, and their specificities > 80%. The best performing index was LV-MPI', with a sensitivity of 91.7% and specificity of 88.6%.

CONCLUSIONS: Before diagnosis of TTTS, the cardiac function (as assessed by MPI and MPI') of the future donor twin is not grossly abnormal, but that of the recipient is abnormal. We identified cardiac indices predictive of the subsequent development of TTTS, and suggest a possible role of these indices in planning the follow-up of monochorionic diamniotic twin pregnancies.