Myocardial infarction in a pregnant woman revealing a transitional deficit in protein S: a rare case report

The occurrence of myocardial ischemia and myocardial infarction in pregnancy is relatively rare, the occurrence of myocardial infarction in pregnancy is associated with cardiovascular risk factors. The deficiency of coagulation regulatory systems in the occurrence of venous thrombosis is well established; however, their role in arterial thrombosis is controversial. Here, we present an interesting case of a 34-year-old of acute myocardial syndrome without persistent ST segment elevation, which revealed transient protein S deficiency. Management of acute coronary syndrome (ACS) during pregnancy may represent a unique clinical challenge. In this manuscript, we review the clinical presentation, anatomic considerations, and management strategy in our patient presenting with ACS. Objective: this case highlights the importance of multimodality approach to help to obtain a more timely diagnosis of myocardial infarction in pregnancy and the importance collaboration between obstetricians, cardiologists, pediatricians and anesthesiologists to ensure optimal care.


Introduction
The occurrence of myocardial ischemia and myocardial infarction (MI) in pregnancy is relatively rare compared to other complications described in various reports on maternal morbidity and mortality. The occurrence of myocardial infarction in pregnancy is associated with cardiovascular risk factors such as arterial hypertension, diabetes, thrombophilia, preeclampsia and a history of myocardial ischemia [1].
The deficiency of coagulation regulatory systems in the occurrence of venous thrombosis is well established; however, their role in arterial thrombosis is controversial [2]. We describe a case of acute myocardial syndrome without persistent ST segment elevation in the per-partum period in a young woman with transient protein S deficiency. We will review the literature for the risk factors related to pregnancy of myocardial infarction.  Figure 1A), no invasive intervention was undertaken. The patient managed on aspirin, IV unfractionated heparin, and clopidogrel while in hospital, and was discharged on aspirin, clopidogrel and heparin and has done well throughout follow-up.

Patient and observation
Given the young age, the pregnancy site and the occurrence of myocardial infarction, a thrombophilia assessment was performed (Table 1). Since obstetric conditions being favorable, a natural delivery was allowed, two weeks after the patient gave birth to a newborn baby of 3100g female with apgar scores at 10/10 minutes of life. After 48 hours of delivery, the patient was transferred to the cardiology department to be monitored in a simple follow-up mode. A control coronarography performed showed the complete disappearance of the thrombotic lesion ( Figure 1B).The patient was treated with warfarin to target an international normalized ratio (INR) of 2.0-3. New biological assessments performed three months after the initial episode, were without any particularity (protein S at 103%). The anticoagulation was stopped, the patient continued under Aspirin 160mg, Carvedelol 6.25 mg ½ x 2/d, Ramipril 2.5 mg/d.

Discussion
Myocardial infarction complicating a pregnancy is a rare event, with a frequency between 3 and 7 of cases per 100,000 deliveries. Mortality associated with myocardial infarction is estimated to be between 5 and 7% [1,3]. Since the year of 2000, the frequency of myocardial infarction has increased by pregnant women. This could be explained by the aging of the obstetrical population, by the recrudescence of cardiovascular risk factor and the easier diagnosis of myocardial infarction clinically unclear by the standardized serum troponin. The underlying triggers of acute myocardial infarction in pregnancy are considered multifactorial and attributable to physiological events occurring during pregnancy. Increased myocardial oxygen demand due to marked increases in blood volume, systolic volume and heart rate, profound changes in coagulation and fibrinolytic system leading to increased risk of thrombosis, physiological anemia and decreased diastolic blood pressure [4]. The constitutional deficits in antithrombin III (AT), protein S (PS), and protein C (PC) result in a predominant activation of coagulation which promotes the appearance of arterial and/or venous thrombosis. Deficits in PS and PC most often result in deep vein thrombosis of the lower limbs complicated or not with pulmonary embolism and cerebral thrombophlebitis, arterial thrombosis being more rare [5,6]. Some authors explain the association of PS deficiency with arterial thrombosis by the fact that the thrombosis resulting from an endothelial lesion is favored by a pre-existing local deficit in PS. The pathogenic mechanisms of PS deficiency that lead to in vivo injury and vessel thrombosis are unknown [6]. The frequency of thrombosis is, respectively, for protein C and S deficiency, respectively, of 3-10% and 0-6% during pregnancy; 7-19% and 7-22% in the immediate postpartum [3,5].
The morphological appearance of coronary arteries following myocardial infarction by pregnant women has been studied by angiography or autopsy mainly in the study published by Roth and El Kayam [3]. The main coronary territory reached is the former territory (70%). Before 1995, the major cause of myocardial infarction was stenosis (43% of cases), the other causes were either thrombosis (21% of cases), coronary dissection (16% of cases) and in 30% of cases coronaries were normal [4]. The atypical symptomatology of myocardial ischemia during pregnancy and the low degree of suspicion in young patients make the diagnosis less clear. The Obstetric and cardiac conditions will determine the mode of delivery.
In both cases, it should be done under intensive monitoring with epidural to reduce labor pains and heart stress. In the case of vaginal delivery, instrumental extraction is recommended in order to limit expulsive maternal efforts which increase myocardial oxygen consumption [9, 10]. The question of long-term anticoagulation after a first arterial thrombotic episode in subjects with a known protein C, S or AT deficiency remains. In the absence of prospective studies, the benefits and risks of such therapy should be assessed individually, depending on the presence of other hereditary or acquired prothrombotic factors, the type and degree of the deficit, the recurrence of the event and family history. Patient follow-up is therefore essential in order to evaluate the long-term impact of these abnormalities and to establish, by remote biological control, the true deficits of the transitional deficits, in order to institute possible measures therapeutic [5,6].

Conclusion
Myocardial infarction is a pathology that is certainly rare in pregnant women but is associated with severe maternal and fetal morbidity and mortality. Immediate and adequate management is necessary to limit the complications that can condemn the vital, functional and/or obstetrical future of these patients. The discovery of a protein S deficiency therefore requires regular monitoring to discuss a secondary prevention treatment if the deficit is confirmed. The management of the patient and her pregnancy involves a close collaboration between obstetricians, cardiologists, pediatricians and anesthesiologists to ensure optimal care.  Table 1: the results of thrombophilia assessments requested