To investigate clinical characteristics of twin pregnancy combined with hypertrophic cardiomyopathy (HCM) and review related literature.

A pregnant woman with a gestational age of 33^{+ 5} gestational weeks who admitted to the Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University with twin pregnancy combined with HCM on October 12, 2017 was included into this study. The clinical data, characteristics and treatment process were retrospectively analyzed, and related literature were reviewed. In this study, the literature review of HCM in twin pregnancy was conducted with the following keywords " hypertrophic cardiomyopathy" " twin pregnancy" " cardiomyopathy" " twin pregnancy" " hypertrophic cardiomyopathy" and " cardiomyopathy" . The search period was set from database inception to January 1, 2020, and the clinical characteristics and treatment protocols of the disease were summarized. This study met the requirements of World Medical Association Declaration of Helsinki revised in 2013.

The clinical data and consultation process of this patient were collected as follows. ①This patient was 30 years old, post-in vitro fertilization-embryo transfer (IVF-ET) (two frozen embryos were transferred), with a history of HCM for 4⁺ years. The patient was repeatedly informed of the risks and after full assessment by the multiple disciplinary team (MDT), the patient underwent regular prenatal check up under the supervision of the Department of Obstetrics and Cardiology. Due to premature rupture of membranes (PROM), the patient underwent an emergency cesarean section at 34^{+ 1} weeks′ gestation under general anesthesia after assessment by the MDT, and the operation was successful. Immediately after surgery, she was transferred to the intensive care unit (ICU) for monitoring. Postoperatively, the patient developed acute heart failure, which stabilized after treatment with respiratory support, sedation, anti-infection, reduction of volume load and improvement of cardiac function, etc.. The patient was evaluated by a cardiovascular specialist and given beta-lactone to control the ventricular rate and reduce myocardial oxygen consumption. Two days after surgery, the condition was improved and this patient was transferred back to the obstetrics ward. She is still being followed up and both mother and baby are in good condition. ②Results of literature review were as follow. According to the literature search strategy of this study, no relevant reports of twin pregnancy combined with HCM were retrieved, so the search was expanded by changing keywords from " twin" to " pregnancy" , and a total of 12 articles were retrieved. Among these 12 articles, a total of 260 cases of pregnancy with HCM were retrieved, involving a total of 284 pregnancies, all of which were singleton pregnancy. Among these 284 pregnancies, 28 cases of heart failure occurred; 2 patients died, and the remaining patients with heart failure were treated effectively and their condition improved. Except for 52 pregnancies in which the neonatal outcome was unknown, there were 46 cases of preterm fetal delivery and 5 cases of intrauterine fetal death in the remaining 232 pregnancies.

Most patients with asymptomatic or mild HCM can tolerate pregnancy and have good maternal and infant outcomes. However, in patients with HCM in multiple pregnancies, even if no maternal adverse cardiovascular events occurred during pregnancy, the rapid change in blood volume after delivery will be a great challenge for patients with cardiomyopathy.