Journal of the American Heart Association ORIGINAL RESEARCH Maternal and Perinatal Outcomes Associated With Extremely High Values for the sFlt-­1 (Soluble fms-­Like Tyrosine Kinase 1)/PlGF (Placental Growth Factor) Ratio Cecilia Villalaín, MD, PhD; Ignacio Herraiz , MD, PhD; Leonor Valle, MD, PhD; Manel Mendoza, MD, PhD; Juan Luis Delgado, MD, PhD; María Vázquez-Fernández, MD; Juan Martínez-Uriarte, MD, PhD; Íñigo Melchor, MD; Sara Caamiña, MD; Antoni Fernández-Oliva, MD; Olga Patricia Villar, MD; Alberto Galindo, MD, PhD BACKGROUND: There is little knowledge about the significance of extremely high values (>655) for the ratio of sFlt-­1 (soluble fms-­like tyrosine kinase 1) to PlGF (placental growth factor). We aim to describe the time-­to-­delivery interval and maternal and perinatal outcomes when such values are demonstrated while assessing suspected or confirmed placental dysfunction based on clinical or sonographic criteria. METHODS AND RESULTS: A multicenter retrospective cohort study was performed on 237 singleton gestations between 20+0 and 37+0 weeks included at the time of first demonstrating a sFlt-­1/PlGF ratio >655. Clinicians were aware of this result, but standard protocols were followed for delivery indication. Main outcomes were compared for women with and without preec- lampsia at inclusion. In those with preeclampsia (n=185, of whom 77.3% had fetal growth restriction), severe preeclampsia features and fetal growth restriction in stages III or IV were present in 49.2% and 13.5% cases, respectively, at inclusion and in 77.3% and 28.6% cases, respectively, at delivery. In the group without preeclampsia (n=52, 82.7% had fetal growth restric- tion), these figures were 0% and 30.8%, respectively, at inclusion and 21.2% and 50%, respectively, at delivery. Interestingly, 28% of women without initial preeclampsia developed it later. The median time to delivery was 4 days (interquartile range: 1–6 days) and 7 days (interquartile range: 3–12 days), respectively (P<0.01). Overall, perinatal mortality was 62.1% before 24 weeks; severe morbidity surpassed 50% before 29 weeks but became absent from 34 weeks. Maternal serious morbidity was high at any gestational age. CONCLUSIONS: An sFlt-­1/PlGF ratio >655 is almost invariably associated with preeclampsia or fetal growth restriction that pro- gresses rapidly. In our tertiary care settings, we observed that maternal adverse outcomes were high throughout gestation, whereas perinatal adverse outcomes diminished as pregnancy advanced. Key Words: fetal growth restriction ■ placental dysfunction ■ placental growth factor ■ preeclampsia ■ sFlt1 A high ratio of sFlt-­ 1 (soluble fms-­ like tyrosine abruptio placentae.4 The higher the value of the sFlt-­1/ kinase-­ 1) to PlGF (placental growth factor) in PlGF ratio, the greater the underlying placental disease maternal serum during the second half of preg- and the shorter time-­to-­delivery interval.2 nancy is related to placental dysfunction (PD),1 includ- The sFlt-­1/PlGF ratio threshold of >655 has been ing preeclampsia,2 fetal growth restriction (FGR),3 and described as the third quartile of the sFlt-­ 1/PlGF Correspondence to: Ignacio Herraiz, MD, PhD, Department of Obstetrics and Gynaecology, Hospital Universitario 12 de Octubre, Avda. Córdoba s/n, Madrid 28041, Spain. E-mail: ignacio.herraiz@salud.madrid.org Supplementary material for this article is available at https://www.ahajo​urnals.org/doi/suppl/​10.1161/JAHA.119.015548 For Sources of Funding and Disclosures, see page 9. © 2020 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-­commercial and no modifications or adaptations are made. JAHA is available at: www.ahajournals.org/journal/jaha J Am Heart Assoc. 2020;9:e015548. DOI: 10.1161/JAHA.119.0155481 Villalaín et al Outcomes With High sFlt-­1/PlGF Ratios preeclampsia in a preterm phase. Even less is known CLINICAL PERSPECTIVE about pregnancies without preeclampsia. When PD debuts at early GAs, expectant management is pur- What Is New? sued, but it is often difficult to predict the course of • This cohort of pregnant women with extremely the disease, and both patients and physicians are high values for the sFlt-1/PlGF ratio (>655) is usually concerned about the threats of prolonging the the largest in which maternal and perinatal out- pregnancy.8 Therefore, it may be of interest to rec- comes are described. ognize the implications for the mother and the fetus of facing extremely high sFlt-­1/PlGF ratios at different What Are the Clinical Implications? stages of pregnancy to better balance the benefits • Median time to delivery was short after an and risks of an expectant attitude. sFlt-1/PlGF ratio >655 was demonstrated, vary- Our aim is to analyze maternal and perinatal out- ing from 4 to 7 days depending on the initial comes in pregnancies with or without preeclampsia in presence or not of preeclampsia. • Maternal serious morbidity was high (>30%) at which an sFlt-­1/PlGF ratio has been requested during any gestational age, whereas perinatal severe the second half of pregnancy in the context of a clin- morbidity and mortality surpassed 50% before ical suspicion of PD and a result of >655 has been 29 to 30 weeks and significantly diminished to obtained. about 15% between 30 and 34 weeks and was null thereafter in our cohort. METHODS The data that support the findings of this study are available from the corresponding author on reason- Nonstandard Abbreviations and Acronyms able request. EFW estimated fetal weight FGR fetal growth restriction Study Design and Population GA gestational age This multicenter observational retrospective cohort HELLP hemolysis, elevated liver enzymes and study was conducted in 9 hospitals in Spain that have low platelet count incorporated use of the sFlt-­ 1/PlGF ratio into clinical NICU neonatal intensive care unit practice as an aid to rule out suspected PD and to sup- PD placental dysfunction port diagnosis and follow-­up. All consecutive singleton PE preeclampsia pregnancies with live and structurally healthy fetuses at these centers from February 2014 to May 2019 with at PlGF placental growth factor least 1 sFlt-­1/PlGF ratio determination >655 between REDCap Research Electronic Data Capture tool 20+0 and 37+0 weeks were included. We excluded sFlt-1 soluble fms-like tyrosine kinase-1 cases with incomplete perinatal outcome. The study STROBE Strengthening the Reporting of was approved by every hospital’s local ethics committee Obser­vational Studies in Epidemiology without requiring informed consent, given that the use of UA umbilical artery angiogenic biomarkers to “aid in diagnosis” is standard practice in Spain,9 in addition to the study’s retrospective character and use of encoded and anonymized data. values in singleton pregnancies diagnosed with early onset preeclampsia and has been associated with a 2.7 increased risk of expeditious delivery (<48 hours) Data Collection, Follow-­Up, and Outcome in those with <655.5 These high values are also found Measures in ≈1% to 2% of women tested for suspicion of pre- Maternal characteristics including age, height, eclampsia.6 Recently, Stolz et al7 compared the peri- weight, smoking status, race, method of conception, natal outcomes in 30 preeclampsia cases with sFlt-­1/ low-­dose aspirin intake, heparin prophylaxis, and risk PlGF >655 and 30 preeclampsia controls with <655 factors for preeclampsia and other PD-­related disor- and matched by gestational age (GA). This small ders, according to the National Institute for Health study could not find significant differences in the peri- and Care Excellence (NICE) guidelines,10 were col- natal outcomes between groups; however, maternal lected from the medical records. GA was estimated complications were not assessed, and cases without according to the American College of Obstetricians preeclampsia were not included. There is little prog- and Gynecologists: reliable last menstrual period nostic information about the significance of exceeding was corrected by the crown–rump length before the threshold of 655 in pregnancies complicated with 14+0 weeks or biparietal diameter from 14+0 to J Am Heart Assoc. 2020;9:e015548. DOI: 10.1161/JAHA.119.0155482 Villalaín et al Outcomes With High sFlt-­1/PlGF Ratios 21+6 weeks, when a significant discrepancy of >7 or including the identification of a retroplacental hema- >10 days was found, respectively.11 toma or evidence of blood clot in at least 20% of its Reasons for assessing the sFlt-­1/PlGF ratio were surface based on clinical data provided by the attend- (1) clinical suspicion of PD, including the presence of ing obstetrician at delivery18); neurological deficits; and signs and symptoms suggestive of preeclampsia,5 ab- eclampsia. If any complication was identified, immedi- normal uterine artery Doppler at 24+0 to 28+6 weeks,12 ate delivery was indicated regardless of GA. Delivery and early onset FGR (diagnosed <32+0 weeks),13 and was also recommended after 34+0 weeks in the pres- (2) serial follow-­up in cases of diagnosed preeclampsia ence of severe features of preeclampsia and in any and FGR.14 The first sample in which an sFlt-­1/PlGF preeclampsia case after 37+0 weeks. ratio >655 was demonstrated was the one selected for analysis. The sFlt-­1 and PlGF concentrations (in pg/ FGR assessment mL) were determined using an automated assay sys- tem (Cobas 6000 e701 module; Roche Diagnostics). Diagnosis, fetal surveillance, timing, and route of de- The sFlt-­1/PlGF ratio was expressed in absolute values. livery followed a stage-­based protocol.19 Fetal weight The obstetricians involved in the management of these was estimated using the Hadlock formula,20 and cen- cases were aware of the results of the sFlt-­1/PlGF ratio. tiles were calculated according to the references es- They knew that the sFlt-­1/PlGF ratio cutoff of ≤38 helps tablished in each center; for the purpose of presenting to rule out preeclampsia5 and that ≥85 aids in diagno- the results in this study, estimated fetal weight (EFW) sis of preeclampsia,15 and >655 is associated with a centiles were homogenized by customization using the high risk of the need to deliver within 48 hours.6 This GROW software.21 Whenever anterograde flow in the information was used for tailored management includ- umbilical artery was present, weekly monitoring (fetal ing risk stratification, planning follow-­up, and allocation Doppler including interrogation of the ductus venosus of patients. However, the indications for delivery were plus conventional cardiotocography) was planned, and intended to be guided by current protocols, regardless vaginal delivery (in the absence of other contraindica- of the results of the sFlt-­1/PlGF ratio. To evaluate the tions) was recommended after 37 weeks. If absent potential influence of the knowledge of the sFlt-­1/PlGF end-­diastolic umbilical artery flow was detected, sub- ratio in clinical management, an independent expert sequent follow-­up controls were performed every 48 to at each center was designated to assess the appro- 72 hours, and elective cesarean section was indicated priateness of clinical decisions. Those included hos- at 34 weeks. When reverse end-­diastolic umbilical ar- pitalization, fetal maturation, indication of iatrogenic tery flow or ductus venosus pulsatility index >95th cen- delivery, and overall adequacy of clinical management. tile was found, hospitalization and daily monitoring were carried out until elective cesarean section at 30 weeks. Whenever a reverse a-­wave flow in the ductus venosus Preeclampsia assessment or spontaneous decelerations in the cardiotocography In cases of suspected PD, the presence of preec- were noted, elective cesarean section was indicated lampsia was evaluated at inclusion and at every visit provided that the GA was ≥26+0 weeks and estimated afterward by measuring blood pressure and determin- fetal weight ≥500 g (if any of these thresholds were not ing proteinuria. For the purpose of this study, a case reached, the decision to deliver was agreed with the was classified as preeclampsia when both hyperten- parents after detailed neonatal counseling). sion and proteinuria were demonstrated, accord- Corticoids for fetal maturity (betamethasone 12 mg/ ing to the National High Blood Pressure Education day for 2 days) were administered before 34+6 weeks Program Working Group on High Blood Pressure in if fetal viability was reached and short-­term delivery Pregnancy.16 However, in the clinical setting, patients was expected, including the presence of severe fea- were managed as having preeclampsia even in the tures of preeclampsia and the loss of anterograde absence of significant proteinuria when other severity end-­diastolic umbilical artery flow and after the demon- criteria were met and indications for delivery followed stration of sFlt-­1/PlGF ratio >655 (if not indicated previ- current recommendations.17 Expectant management ously). A repeated cycle of corticoids was considered was initially attempted for fetal interest whenever after 1 week of the administration of the first cycle if the the GA was ≥24 weeks and was discussed with the GA remained below 34+6 weeks. Magnesium sulfate parents at earlier weeks. During expectant manage- for fetal neuroprotection was indicated when there was ment, maternal complications were assessed, in- a risk of imminent delivery at 31+6 weeks or less and cluding pulmonary edema; refractory hypertension; was not being administered for maternal indication. complete or incomplete HELLP (hemolysis, elevated Perinatal data including date and mode of delivery, liver enzymes, and low platelet count) syndrome; ol- birth weight, Apgar test at 5 minutes, arterial cord pH, iguria <500 mL/24 hours; abruptio placentae (defined neonatal intensive care unit admission, severe morbid- as placental detachment before delivery of the fetus, ity at discharge home (bronchopulmonary dysplasia, J Am Heart Assoc. 2020;9:e015548. DOI: 10.1161/JAHA.119.0155483 Villalaín et al Outcomes With High sFlt-­1/PlGF Ratios hypoxic-­ischemic encephalopathy, intraventricular hem- A orrhage grade ≥3, cystic periventricular leukomalacia, necrotizing enterocolitis, sepsis, and retinopathy of pre- maturity), and mortality were recorded. Postnatal fol- low-­up for at least 6 months was available for all survivors. Outcome data were recorded by all centers in a common database created on the Research Electronic Data Capture (REDCap) tool22 hosted at the “imas12” research institute. Statistical Analysis Sample size was estimated for a 5% significance level and 80% power, basing our calculations in a prior study that determined cases with suspected preec- lampsia before 34 weeks and sFlt-­1/PlGF higher than B the third tertile had a 78% chance of developing an adverse outcome.23 We calculated that 104 cases (52 with preeclampsia and 52 without preeclampsia at in- clusion) were required to identify a difference >25% in severe maternal and perinatal outcomes. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement was fol- lowed for reporting the results. Continuous variables were expressed as mean (SD) or median (interquartile range) when nonnormally distributed. Categorical vari- ables were expressed as percentage. Univariate com- parisons between cases with and without preeclampsia at diagnosis were performed using the Student t test or the Mann–Whitney U test for continuous variables and the χ2 or Fisher exact test for categorical variables. Figure 1. Progression of fetal growth restriction (FGR) from inclusion with sFlt-­1 (soluble fms-­like tyrosine kinase 1)/PlGF Kaplan–Meier survival curves were generated for the (placental growth factor) ratio >655 to delivery in cases with analysis of the time to delivery after the demonstration preeclampsia (A) and without preeclampsia (B) at inclusion. of sFlt-­1/PlGF >655. A 2-­sided P<0.05 was considered statistically significant. Data were carefully entered and at inclusion, as shown in Table 1, except for a higher analyzed after data cleansing, using the STATA statisti- proportion of prior preeclampsia in the preeclampsia cal package, version 14.1 (StataCorp). group. Main perinatal characteristics are depicted in Table 2. Most cases (82.7%) classified as without pre- eclampsia at inclusion were normotensive at the sFlt-­1/ RESULTS PlGF determination. Women with preeclampsia at the An sFlt-­1/PlGF ratio >655 was identified in 242 single- time of obtaining an sFlt-­1/PlGF ratio >655 had higher ton pregnancies during the study period, among which GA of 29.4 versus 27.7 weeks (P<0.01) but lower 5 neonates were lost to follow-­up and were excluded median latency time until delivery of 4 versus 7 days from further analysis, leaving a study population of 237 (P<0.01) than those without preeclampsia at inclu- cases. At the time of the first sFlt-­1/PlGF ratio >655, 185 sion. At 48 hours, 60.5% and 82.7% women remained women had preeclampsia (78.1%). Of them, 49.2% had pregnant, respectively (Figure 2). This still resulted in severe features of preeclampsia, 77.3% had FGR, and a higher GA at delivery (30.1 versus 28.9 weeks) and 13% had FGR in stage III or IV. At delivery, these val- higher birth weight (1079 versus 828 g) in the cases ues were 77.3%, 84.9%, and 28.6%, respectively. The that already had preeclampsia. Reasons for delivery remaining 52 cases without preeclampsia at inclusion varied between groups: in the group with preeclamp- had mainly FGR (82.7%), 21.2% in stage III or IV. At de- sia at inclusion (versus no preeclampsia), a higher livery, these values were 90.4% and 50%, respectively. proportion of deliveries due to maternal complications Moreover, 23 of these women developed preeclampsia (50.8% versus 21.2%, P<0.01) and a lower propor- (44.2%), 16 with severe features (30.8%; Figure 1). tion due to fetal deterioration (41.6% versus 59.6%, There were no differences in the baseline character- P<0.01) were found. We made a further analysis of istics between women with and without preeclampsia the time until delivery in the group of women without J Am Heart Assoc. 2020;9:e015548. DOI: 10.1161/JAHA.119.0155484 Villalaín et al Outcomes With High sFlt-­1/PlGF Ratios Table 1. Baseline Characteristics of the Study Population Stratified by the Presence of Preeclampsia at the Time of Demonstration of sFlt-­1/PlGF >655 Preeclampsia at Inclusion Characteristics Total (N=237) No (n=52) Yes (n=185) P Value Maternal age, y 33.7±5.8 32.0±6.1 31.6±5.8 0.49 Height, cm 161.1±9.1 162.2±7.3 159.7±8.5 0.09 Prepregnancy weight, kg 69.1±15.2 71.0±17.0 68.9±14.8 0.59 2 Prepregnancy BMI, kg/m 26.7±6.4 26.5±6.0 26.6±6.0 0.96 Smoking status Current 7 (3.0) 1 (1.9) 6 (3.3) 0.16 Cigarettes/d, median (range) 9 (3–20) 8 (3–24) 10 (4–20) Race or ethnic group† White 169 (71.3) 42 (80.8) 127 (68.7) Hispanic 35 (14.8) 7 (13.5) 28 (15.1) Asian 5 (2.1) 0 (0) 5 (2.7) 0.60 Black 11 (4.6) 1 (1.9) 10 (5.4) Arab 14 (5.9) 2 (3.8) 12 (6.5) Other 3 (0.4) 0 (0) 3 (1.6) Risk factors for PD High Previous preeclampsia 25 (10.5) 0 (0) 25 (13.5) 0.01 Chronic hypertension 30 (12.7) 4 (7.7) 26 (14.1) 0.22 Prepregnancy diabetes mellitus 1 (0.4) 0 (0) 1 (0.54) 0.60 Chronic kidney disease 4 (1.7) 0 (0) 4 (2.2) 0.49 Thrombophilia 5 (2.1) 1 (1.9) 4 (2.2) 0.92 Systemic lupus erythematosus 3 (1.3) 0 (0) 3 (1.6) 0.11 Moderate Nulliparity 159 (67.1) 34 (65.4) 125 (67.6) 0.77 Age ≥40 y 13 (16.7) 3 (5.8) 10 (5.4) 0.92 Prepregnancy BMI ≥35 23 (10.0) 5 (9.6) 18 (9.7) 0.98 Family history of preeclampsia* 7 (3.0) 0 (0) 7 (3.8) 0.35 ≥1 High-­risk or 2 moderate-­risk factors 74 (31.2) 11 (21.2) 64 (34.6) 0.07 Mode of conception Spontaneous 215 (90.7) 46 (88.5) 165 (89.2) In vitro fertilization 16 (6.8) 6 (11.5) 10 (5.4) 0.06 Oocyte donation 6 (2.5) 0 (0) 6 (3.2) Low-­dose aspirin intake (100 mg/d) No 204 (86.4) 45 (86.5) 158 (85.4) 0.68 Starting at or before 16 wk 29 (12.3) 7 (13.5) 22 (11.9) Starting after 16 wk 3 (1.3) 0 (0) 3 (1.6) Low-­dose heparin prophylaxis No 210 (88.6) 47 (90.4) 163 (88.1) Starting at or before 16 wk 6 (2.5) 1 (1.9) 5 (2.7) 0.89 Starting after 16 wk 21 (8.9) 4 (7.7) 17 (9.2) Data are mean±SD or n (%), unless otherwise stated. BMI indicates body mass index; PD, placental dysfunction; PlGF, placental growth factor; and sFlt-­1, soluble fms-­like tyrosine kinase 1. *First-­degree relative (mother or sister) with a history of preeclampsia. † Evaluated after Bonferroni adjustment. preeclampsia at inclusion, dividing them in 2 sub- in this latency period between them (7 days [interquar- groups depending on the final presence or absence of tile range: 4–14] and 7 days [interquartile range: 3–13], preeclampsia, and we did not observe any difference respectively), as shown in Figure S1. J Am Heart Assoc. 2020;9:e015548. DOI: 10.1161/JAHA.119.0155485 Villalaín et al Outcomes With High sFlt-­1/PlGF Ratios Table 2. Main Perinatal Outcomes of the Study Population Stratified by the Presence of Preeclampsia at the Time of Demonstration of sFlt-­1/PlGF >655 Preeclampsia at Inclusion Perinatal Outcome Total (N=237) No (n=52) Yes (n=185) P Value GA at diagnosis, median (Q1–Q3) 29.0 (3.3) 27.7 (25.6–30.4) 29.4 (27.1–31.9) <0.01 GA at delivery, median (Q1–Q3) 29.8 (3.3) 28.9 (27.1–31.5) 30.1 (27.8–32.5) 0.03 Time to delivery, median (IQR) 4 (2–10) 7 (4–13) 4 (1–6) <0.01 sFlt-­1/PlGF, median (IQR) 823 (718–1051) 818 (725–1064) 823 (712–1048) 0.92 Mean arterial pressure, mm Hg 110±13 101±9 112±12 <0.01 Hypertension (SBP ≥140 or DBP >90 mm Hg) 195 (78.1) 10 (19.5) 185 (100) <0.01 Reason for delivery Spontaneous onset 1 (0.4) 0 (0) 1 (0.5) PPROM 2 (0.8) 1 (1.9) 1 (0.5) Maternal indication due to preeclampsia 105 (44.4) 11 (21.2) 94 (50.8) <0.01 Fetal indication due to FGR 108 (45.4) 31 (59.6) 77 (41.6) Abruptio placentae 15 (6.3) 6 (11.5) 9 (4.8) Other 6 (2.5) 3 (5.8) 3 (1.6) Intrauterine demise 21 (8.9) 10 (19.2) 11 (6.9) <0.01 Neonatal mortality 15 (6.3) 5 (9.6) 10 (5.4) 0.28 Overall perinatal mortality 36 (15.2) 15 (28.8) 21 (11.4) <0.01 Neonatal weight 1024±445 828±438 1079±432 <0.01 NICU admission 193 (81.4) 39 (75.0) 154 (83.2) 0.27 Days at NICU 37.6±29.2 47.8±32.8 36.1±28.2 0.21 Neonatal severe morbidity* Any 74 (34.3) 18 (42.9) 56 (32.2) 0.19 Sepsis 47 (21.8) 13 (31.0) 34 (19.5) 0.11 Bronchopulmonary dysplasia 32 (14.8) 7 (16.7) 25 (14.4) 0.61 Necrotizing enterocolitis 11 (5.1) 3 (7.1) 8 (4.6) 0.50 Periventricular leukomalacia 5 (2.3) 1 (2.4) 4 (2.3) 0.97 Retinopathy (stage III–V) 12 (5.6) 4 (9.5) 8 (4.6) 0.21 IVH grade III or IV 6 (2.8) 1 (2.4) 5 (2.9) 0.86 Maternal severe morbidity Any 99 (41.8) 19 (36.5) 80 (43.2) 0.39 Severe hypertension 39 (16.5) 3 (5.8) 36 (19.5) 0.02 HELLP syndrome 28 (11.8) 3 (5.8) 25 (13.5) 0.13 Abruptio placentae 27 (11.4) 11 (21.2) 16 (8.7) 0.01 Oliguria (<500 mL/24 h) 15 (6.3) 0 (0) 15 (8.1) 0.03 Pulmonary edema 7 (3.0) 1 (1.9) 6 (3.2) 0.62 IDC 2 (0.8) 0 (0) 2 (1.1) 0.45 Eclampsia 3 (1.3) 0 (0) 3 (1.6) 0.36 Myocardial infarction 1 (0.4) 1 (1.9) 0 (0) 0.06 Data are mean±SD or n (%), unless otherwise stated. DBP indicates diastolic blood pressure; FGR, fetal growth restriction; GA, gestational age; HELLP, hemolysis, elevated liver enzymes, and low platelet count; IDC, intravascular disseminated coagulopathy; IQR, interquartile range; IVH, intraventricular hemorrhage; NICU, neonatal intensive care unit; PlGF, placental growth factor; PPROM, preterm premature rupture of membranes; Q, quartile; SBP, systolic blood pressure; and sFlt-­1, soluble fms-­like tyrosine kinase 1. *Calculated among neonatal survivors. Severe maternal morbidity was observed in 99 cases 5.8%, P=0.02) and oliguria (8.1% versus 0%, P=0.03), (44.1%). As depicted in Table 3, a high percentage of whereas those without initial preeclampsia more often maternal complications remained present even after had abruptio placentae (21.2% versus 8.7%, P=0.01). 34 weeks. Women with preeclampsia at inclusion fre- There were 21 cases (8.9%) of intrauterine demise, quently developed severe hypertension (19.5% versus more common in women without preeclampsia at J Am Heart Assoc. 2020;9:e015548. DOI: 10.1161/JAHA.119.0155486 Villalaín et al Outcomes With High sFlt-­1/PlGF Ratios current protocols. However, fetal maturation was an- ticipated in 14 cases (5.9%), hospital admission in 14 (5.9%), and iatrogenic delivery in 23 (9.7%) because of the knowledge of the sFlt-­1/PlGF ratio. When overall management was evaluated, the independent obste- trician expert deemed modified actions to be correct in 8.4% and incorrect in 3% (Table S1). DISCUSSION Main Findings Extremely high values of the sFlt-­1/PlGF ratio (>655) are invariably associated with PD, usually of early onset and quickly worsening. The median time to delivery is 4 or 7 days, depending on the presence or absence, Figure 2. Kaplan–Meier survival estimates of the time to respectively, of preeclampsia when the result is ob- delivery from inclusion with sFlt-­1 (soluble fms-­like tyrosine kinase 1)/PlGF (placental growth factor) ratio >655, stratified tained. The risk for maternal serious morbidity is high by the presence of preeclampsia (PE). at any GA (>30%), as is the risk for perinatal severe morbidity and mortality before 29 to 30 weeks (>50%). However, the latter diminishes thereafter without find- inclusion and most related to previable severe FGR. ing any severe morbidity after 34 weeks. These out- Only 6 of 21 cases (28.6%) reached criteria for active comes do not differ significantly between cases with management. There were also 15 of 216 cases (6.9%) and without preeclampsia at the time of the first sFlt-­1/ of neonatal mortality among live births, and 74 of 216 PlGF ratio >655. cases (34.3%) of overall severe neonatal morbidity. There were no differences regarding neonatal mor- Interpretation of Results tality or morbidity when stratifying by the presence of The main clinical application of the sFlt-­1/PLGF ratio preeclampsia at inclusion. As shown in Table 3, neo- is ruling out preterm preeclampsia.5 However, less natal complications were most frequent when a sFlt-­1/ evidence suggests how to interpret the detection of PlGF value >655 was obtained before 28 weeks. From pathologic values and what they entail for clinical man- 29 weeks onward, there were no cases of neonatal agement. It is known that abnormal values of sFlt-­1/ death, and severe morbidity decreased to 19.6% and PlGF are good indicators of PD, increasing not only in became absent at 34 weeks. Maternal morbidity re- preeclampsia but also in FGR and abruptio placentae. mained high even after 34 weeks. In our series, we Furthermore, the magnitude of the elevation correlates found 1 case of both refractory severe hypertension inversely with the time-­to-­delivery interval. The original and eclampsia and 2 cases of refractory severe hyper- study that evaluated the cutoff of 655 in 24 cases of tension and pulmonary edema. early onset preeclampsia in which the physicians were External analysis of the clinical management showed blinded to this result showed that after 48 hours, only that most decisions (86.5%) were made according to 29.4% women remained pregnant.6 Our larger series, Table 3. Maternal and Perinatal Complications Stratified by GA at Inclusion With sFlt-­1/PlGF >655 Neonatal Severe Adverse Outcome GA et Inclusion, wks No. of Cases Maternal Morbidity Any Intrauterine Demise Neonatal Demise* Severe Morbidity † ≤24 29 13 (44.8) 26 (89.7) 12 (41.3) 6 (26.1) 8 (72.7) 25–26 38 23 (60.5) 31 (81.6) 7 (18.4) 7 (22.5) 17 (70.8) 27–28 51 20 (39.2) 33 (64.7) 1 (2.0) 2 (0.4) 30 (62.5) 29–30 50 24 (48.0) 10 (20.0) 0 (0) 0 (0) 10 (38.5) 31–32 42 14 (33.3) 7 (16.6) 1 (2.4) 0 (0) 6 (14.6) 33–34 17 6 (35.3) 3 (17.6) 0 (0) 0 (0) 3 (17.6) 35–37 10 3 (30.0) 0 (0) 0 (0) 0 (0) 0 (0) GA, gestational age; PlGF, placental growth factor; and sFlt-1, soluble fms-like tyrosine kinase 1. *Among liveborn children. † Among perinatal survivors. J Am Heart Assoc. 2020;9:e015548. DOI: 10.1161/JAHA.119.0155487 Villalaín et al Outcomes With High sFlt-­1/PlGF Ratios in which the physicians were aware of the results, dem- data further ratify experts’ recommendations regard- onstrates that this percentage is higher than expected ing immediate referral to a tertiary care hospital for (60.5% remained pregnant after 48 hours). Our study these patients, admission for close surveillance, and also shows that preeclampsia may be absent in about administration of corticosteroids for fetal maturation, 1 in 5 cases of sFlt-­1/PlGF >655, and in these cases, which should be strongly considered when fetal via- latency until delivery is longer (50% remained pregnant bility has been reached. Moreover, from the clinical after 1 week). In any case, the interval to delivery is point of view, in light of our results, we believe that crucially shortened when extremely high values are future research should take into account these ex- obtained, usually occurring at very early GAs. Fetal treme values of the sFlt-­1/PlGF ratio in the decision deterioration was quick in both groups, and 36.5% of of delivery, especially when reaching 34 weeks, given cases that did not initially present with FGR developed the crossover of maternal and perinatal major compli- it before delivery. Among those with FGR at inclusion, cations seen beyond this time point. 38.3% progressed to a poorer stage and 45.4% of pregnancies required immediate delivery for fetal de- terioration. We believe that these findings also support Strengths and Limitations the assertion that the classical conceptions of preec- The main potential bias in this study is that clinicians lampsia and FGR as separate conditions is artificial were not blinded to the sFlt-­ 1/PlGF ratio; therefore, and that, according to current knowledge, both entities management could have been influenced by its result should be considered as different manifestations of the and by the experience of the group using biomarkers. same PD. We have shown that an extreme angiogenic Nevertheless, the inclusion of different hospitals may imbalance reflects a status of severe PD, in which there better reflect the influence of this tool in the real world is a high risk of developing a broad spectrum of ma- compared with the experience of a single center. To ap- ternal and fetal complications that must be assessed proximate the magnitude of the bias due to knowledge comprehensively, regardless of whether or not a reli- of the results, we carried out an external evaluation of able diagnosis of preeclampsia has been reached. each case, observing that certainly only in a minority Given abrupt fetal worsening leading to short la- of the cases the clinical decisions were influenced by tency until delivery, GA at sFlt-­ 1/PlGF >655 shows the use of biomarkers. This accounted for an additional great correlation with perinatal results. It is import- 6% of hospitalized cases, 5.9% of administering cor- ant that both clinicians and parents are aware that if ticosteroids for fetal maturation, and 9% of anticipat- a value >655 is detected before 24 weeks, perinatal ing delivery, compared to what it was expected if only mortality and severe perinatal morbidity can be as high conventional criteria had been followed. This result is as 62% and 90%, respectively. Conversely, perinatal in accordance with another study24 that evaluated the results improve drastically when an sFlt-­1/PlGF >655 impact of the awareness of angiogenic biomarkers in is detected from 29 weeks, with much lower rates of suspected preeclampsia regarding additional hospi- perinatal mortality and severe morbidity. talizations (5.9%) and fetal maturation (7.7%). The an- GA is not so crucial when considering maternal out- ticipated delivery was lower (1.7%) than ours but was comes; severe maternal morbidity was found in 41.8% conducted in the setting of suspected preeclampsia, of cases and remained high even when the sFlt-­1/PlGF where the values of the sFlt-­1/PlGF ratio were far from ratio >655 was found after 34 weeks. Notably, 12% 655 in most cases. We have not compared our cases of cases developed a HELLP syndrome and 11% had with others that did not reach such high values for the abruptio placentae. Therefore, these complications sFlt-­1/PlGF ratio because that would have implied a should be particularly monitored by increasing the fol- different study design. In addition, this retrospective low-­up controls for their early detection before they be- study is subject to information, selection, and confu- come clinically manifest. sion biases. Caution should be taken not to generalize The highest incidence of our cases was found be- our findings to more diverse populations; our sample tween 28 and 30 weeks, similar to Stolz et al.7 At these was mainly composed of white and Hispanic women. early GAs, expectant management is usually pursued Similarly, we acknowledge that the results reflect the in the absence of features of imminent complications performance of highly specialized hospitals and thus to favor fetal prognosis. In light of our results, this aim may not be extrapolated to other types of centers. can be seriously compromised when extremely high Furthermore, this study was based only in the first values for the sFlt-­1/PlGF ratio are detected. Although determination >655 and did not consider serial meas- Stolz and colleagues proposed that levels >1000 urements to evaluate the progression of angiogenic were more reliable to predict perinatal adverse out- biomarkers; however, the short time to delivery in most comes than 655, they did not consider the substan- of these cases precludes such longitudinal follow-­up. tial maternal adverse outcomes underlying a sFlt-­1/ Even considering these limitations, we must remark PlGF ratio >655 that we found in our study. Thus, our that this cohort is the largest to date describing the J Am Heart Assoc. 2020;9:e015548. DOI: 10.1161/JAHA.119.0155488 Villalaín et al Outcomes With High sFlt-­1/PlGF Ratios course of patients with these extremely high values for 5. Verlohren S, Herraiz I, Lapaire O, Schlembach D, Moertl M, Zeisler H, Calda P, Holzgreve W, Galindo A, Engels T, et al. The sFlt-­1/PlGF ratio in different the sFlt-­1/PlGF ratio. Even though our results lack the types of hypertensive pregnancy disorders and its prognostic potential in evidence to support changes in current clinical prac- preeclamptic patients. Am J Obstet Gynecol. 2012;206:58.e1–58.e8. tice, they could be of interest in inspiring the design 6. Zeisler H, Llurba E, Chantraine F, Vatish M, Staff AC, Sennström M, Olovsson M, Brennecke SP, Stepan H, Allegranza D, et al. Predictive of further clinical trials to test whether revealing bio- value of the sFlt-­1:PlGF ratio in women with suspected preeclampsia. N marker levels would affect clinical outcome and sup- Engl J Med. 2016;374:13–22. port decision-­making based on the use of biomarkers, 7. Stolz M, Zeisler H, Heinzl F, Binder J, Farr A. An sFlt-­1:PlGF ratio of 655 is not a reliable cut-­off value for predicting perinatal outcomes in women such as the recently published stepped-­wedge trial.25 with preeclampsia. Pregnancy Hypertens. 2018;11:54–60. In conclusion a sFlt-­1/PlGF value >655 must alert 8. Haddad B, Sibai BM. Expectant management in pregnancies with se- clinicians who should closely monitor both mothers vere preeclampsia. Semin Perinatol. 2009;33:143–151. 9. Lapaire O, Shennan A, Stepan H. The preeclampsia biomarkers soluble and fetuses and consider fetal maturation and mater- fms-­like tyrosine kinase-­1 and placental growth factor: current knowl- nal hospitalization given the short time to delivery due edge, clinical implications and future application. Eur J Obstet Gynecol to the high risk of imminent severe adverse outcomes, Reprod Biol. 2010;151:122–129. 10. The National Institute for Health and Care Excellence (NICE). including HELLP syndrome, abruptio placentae, and Hypertension in pregnancy: diagnosis and management. NICE rapid progression of the FGR sequence of deterioration. Guidelines (NG133). 2019. www.nice.org.uk. Available at: https://www. nice.org.uk/guida​nce/ng133. Accessed March 15, 2020. 11. Committee on Obstetric Practice, the American Institute of Ultrasound in Medicine, and the Society for Maternal-Fetal Medicine. Committee ARTICLE INFORMATION opinion No 700: methods for estimating the due date. Obstet Gynecol. Received January 6, 2020; accepted March 2, 2020. 2017;129:e150–e154. 12. Herraiz I, Simón E, Gómez-Arriaga PI, Quezada MS, García-Burguillo Affiliations A, López-Jiménez EA, Galindo A. Clinical implementation of the sFlt-­1/ From the Fetal Medicine Unit-SAMID, Department of Obstetrics and PlGF ratio to identify preeclampsia and fetal growth restriction: a pro- Gynaecology, Hospital Universitario 12 de Octubre, Instituto de Investigación spective cohort study. Pregnancy Hypertens. 2018;13:279–285. Hospital 12 de Octubre (imas12), Universidad Complutense de Madrid, 13. Gordijn SJ, Beune IM, Thilaganathan B, Papageorghiou A, Baschat AA, Madrid, Spain (C.V., I.H., O.P.V., A.G.); Department of Obstetrics, Hospital Baker PN, Silver RM, Wynia K, Ganzevoort W. Consensus definition of Universitario Materno-Infantil de Las Palmas de Gran Canaria, Las Palmas fetal growth restriction: a Delphi procedure. Ultrasound Obstet Gynecol. de Gran Canaria, Spain (L.V.); Department of Obstetrics, Maternal-Foetal 2016;48:333–339. Medicine Unit-SAMID, Vall d’Hebron University Hospital, Universitat 14. Herraiz I, Quezada MS, Rodriguez-Calvo J, Gómez-Montes E, Villalaín Autònoma de Barcelona, Barcelona, Spain (M.M.); Department of Obstetrics C, Galindo A. Longitudinal change of sFlt-­ 1/PlGF ratio in singleton and Gynecology, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain pregnancy with early-­onset fetal growth restriction. Ultrasound Obstet (J.L.D.); Department of Obstetrics, Hospital Universitario Central de Asturias, Gynecol. 2018;52:631–638. Asturias, Spain (M.V.-F.); Department of Obstetrics and Gynecology, Hospital 15. Verlohren S, Herraiz I, Lapaire O, Schlembach D, Zeisler H, Calda P, General Universitario Santa Lucía, Cartagena, Spain (J.M.-U.); Obstetrics Sabria J, Markfeld-Erol F, Galindo A, Schoofs K, et al. New gestational and Gynecology Department, Biocruces Bizkaia Health Research Institute, phase-­specific cutoff values for the use of the soluble fms-­like tyro- Cruces University Hospital (UPV/EHU), Vizcaya, Spain (Í.M.); Department sine kinase-­1/placental growth factor ratio as a diagnostic test for pre- of Obstetrics and Gynecology, Hospital Universitario Nuestra Señora de la eclampsia. Hypertension. 2014;63:346–352. Candelaria, Santa Cruz de Tenerife, Spain (S.C.); Maternal-Foetal Medicine 16. Report of the National High Blood Pressure Education Program Working Unit, Department of Obstetrics and Gynecology, Hospital de la Santa Creu i Group on high blood pressure in pregnancy. Am J Obstet Gynecol. Sant Pau, Barcelona, Spain (A.F.-O.). 2000;183:S1–S22. 17. ACOG Practice Bulletin No. 202: gestational hypertension and pre- Sources of Funding eclampsia. Obstet Gynecol. 2019;133:e1–e25. None. 18. Ananth CV, Berkowitz GS, Savitz DA, Lapinski RH. Placental abruption and adverse perinatal outcomes. JAMA. 1999;282:1646–1651. Disclosures 19. Figueras F, Gratacos E. Update on the diagnosis and classification of fetal growth restriction and proposal of a stage-­based management Herraiz, Galindo, Mendoza, and Valle have received lecture fees and con- protocol. Fetal Diagn Ther. 2014;36:86–98. sultancy payments from Roche Diagnostics. The remaining authors have no 20. Hadlock FP, Harrist RB, Sharman RS, Deter RL, Park SK. Estimation disclosures to report. of fetal weight with the use of head, body, and femur measurements a Supplementary Materials prospective study. Am J Obstet Gynecol. 1985;151:333–337. 21. Gardosi J, Francis A. Customized weight centile calculator. GROW ver- Table S1 sion 8.0.1, 2018. Gestation Network, www.gesta​tion.net. Available at: Figure S1 https://www.gesta​tion.net/cc/6/884259.htm. Accessed March 15, 2020. 22. Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. 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Clinical decisions after knowledge of sFlt- Total Preeclampsia at inclusion 1/PlGF >655 (n=237) No (n=52) Yes p (n=185) Hospitalization - No 30 (12.7) 15 (28.8) 15 (8.1) - Previously hospitalized 149 (62.9) 19 (36.5) 130 (70.3) <0.01 - Yes, following current protocols 44 (18.6) 11 (21.2) 33 (17.8) - Yes, conditioned by the knowledge of the 14 (5.9) 7 (13.5) 7 (3.8) sFlt-1/PlGF Fetal maturation - No 36 (15.2) 14 (26.9) 22 (11.9) - Yes, previously indicated 146 (61.6) 25 (48.1) 121 (65.4) 0.02 - Yes, following current protocols 41 (17.3) 8 (15.4) 32 (17.3) - Yes, conditioned by the knowledge of the 14 (5.9) 5 (9.6) 6 (3.2) sFlt-1/PlGF Indication of delivery - Spontaneous onset of labor 2 (0.8) 0 (0) 2 (0.1) - Iatrogenic, following current protocols 212 (89.5) 47 (90.4) 165 (89.2) 0.99 - Iatrogenic, conditioned by the knowledge of 23 (9.7) 5 (9.6) 18 (9.7) the sFlt-1/PlGF Overall adequacy - Correct, according to current protocols 205 (86.5) 41 (78.8) 164 (88.6) - Correct but not following current protocols 20 (8.4) 8 (15.4) 12 (6.5) 0.22 - Incorrect 7 (3.0) 2 (3.8) 5 (2.7) - Unable to establish 5 (2.1) 1 (1.9) 4 (2.2) Figure S1. Time until delivery according to the presence of PE at inclusion or its subsequent development.