L’Écuyer É, Codsi E, Mongeon FP, Dore A, Morin F, Leduc L.J Matern Fetal Neonatal Med. 2021 Oct 15:1-6. doi: 10.1080/14767058.2021.1990883. PMID: 34651531
Take Home Points:
Pregnancy causes important physiologic stress for women with hypertrophic cardiomyopathy, prematurity and small for gestational age are associated complications. Left ventricular outflow tract obstruction is associated with adverse cardiac events including arrythmias or heart failure. Treated obstructive cardiomyopathy constitutes a subgroup of patients at high risk of severe small for gestational age and deserves a close surveillance. Therefore, fetal growth surveillance with ultrasound, early in the third trimester and doppler studies to assess the utero-placental perfusion in the second and third trimesters are warranted in all patients with hypertrophic cardiomyopathy regardless of the severity of their condition.
Hypertrophic cardiomyopathy (HCM) is one of the most frequently inherited heart diseases, affecting approximately 1 in 500 adults. According to the modified World Health Organization (WHO) classification of cardiovascular risk in pregnancy, HCM is considered as class II-III and class IV when there is severe LVOT obstruction, reflecting increased morbidity and mortality in this patient population.
Commentary from Dr. Manoj Gupta (New York City, NY, USA), chief section editor of Pediatric & Fetal Cardiology Journal Watch.
Materials and Methods
All pregnancies with a prior diagnosis of HCM were included. This diagnosis was based on the following criteria: asymmetric left ventricle wall thickness 15mm with or without left ventricular outflow tract (LVOT) obstruction defined by a peak pressure gradient >30 mmHg between the LVOT and the aorta. Subjects were divided in 2 groups based on their peak LVOT gradient measured during the 2nd or 3rd trimester (30 versus >30 mm Hg). Adverse cardiac outcomes abstracted for analysis were heart failure defined as the need for a diuretic, arrhythmias, acute pulmonary edema, severe pulmonary hypertension, thromboembolic event, stroke, myocardial infarction and maternal death. Preterm birth was defined as delivery prior to 37 weeks. Small for gestational age (SGA) was defined as a birthweight.
The mode of delivery was similar in both groups. Assisted vaginal delivery was common in women with HCM to prevent the adverse consequences of Valsalva efforts. The rate of cesarean section was similar in both groups. An increased rate of preterm birth in this cohort (obstructive HCM: 64%; non obstructive HCM: 53%) was observed. Preterm delivery was most commonly iatrogenic in women with obstructive HCM, either for a maternal cardiac event (40%) or the presence of SGA (60%). Most deliveries were late preterm between 34 and 36 6/7 weeks gestation
Cardiac events occurred only in women with obstructive HCM (42% versus 0%; p ¼ .006). Supraventricular arrhythmia developed during pregnancy in women with LVOT gradients between 30 and 50 mm Hg while heart failure complicated pregnancies when the LVOT gradient was above 50 mmHg.
Our results suggest that risk associated with childbearing are acceptable in women with HCM. Preterm delivery and SGA may complicate the pregnancy regardless of the presence of LVOT obstruction. Factors other than LVOT obstruction may impact fetal growth. Adverse cardiac events such as arrhythmias or heart failure mainly occur in the presence of LVOT obstruction.
From our small cohort, the most severe SGA at birth were reported in a sub-group of our patients. A majority of these women had prior cardiac intervention to treat LVOT obstruction because of the severity of the disease.
The authors findings suggest that the risks associated with pregnancy are acceptable in women with HCM. Careful fetal growth surveillance in the third trimester must be addressed as severe SGA may be associated with HCM. LVOT obstruction may be associated with the occurrence of arrhythmia or heart failure during pregnancy