Coronary artery dissection during pregnancy

Acute myocardial infarction complicates approximately 1 per 10 000 pregnancies (1). It clearly causes an increment in both maternal (45%) and fetal mortality, especially reaching the highest levels in the third trimester (50%) (2). Obstructive and non-obstructive coronary arteriopaties are included in the pathogenesis of myocardial infarction, and spontaneous coronary artery dissections, among the non-obstructive coronary arteriopaties, may play a role in very rare cases. The exact etiology of spontaneous coronary artery dissections is unknown. It mostly occurs in young healthy people, and can be associated with pregnancy or with the postpartum period. A case of acute myocardial infarction during the third trimester associated with spontaneous coronary artery dissection while using oral ritodrine for preterm labor is reported, and a computer-assisted literature review of this clinical entity is presented. A 24-year-old, gravida 2, para 1, 35 weeks pregnant woman was referred to our Department of Obstetrics and Gynecology complaining of resting severe retrosternal chest pain and with the suspicious of an acute myocardial infarction. She had no known risk factors such as hypertension, diabetes mellitus, hypercholesterolemia, smoking and no relatives with a history of coronary artery disease. Within the last week, she had being using oral ritodrine (Prepar 10 mg, 20 tb, Eczacibasi) 12 times a day (12 × 10 mg) for preterm labor, which had been prescribed by a previous hospital. She had a healthy female child, born in 1998 via a normal vaginal delivery, and she had no symptoms of coronary artery disease during her pregnancy. On admission to our delivery ward, electrocardiography and serum cardiac enzymes confirmed a diagnosis of a large Q-wave anterior acute myocardial infarction. Creatine kinase CK-MB isoform, troponin T and troponin I were 68.0 ng/mL (normal: 0.0–5.0 ng/mL), 6.7 ng/mL (normal: 0.0–0.1 ng/mL) and 42.1 ng/mL (normal: 0–1 ng/mL), respectively. Serum biochemistry and blood cell count were within a normal range. Vital sings were stable except for a minimal elevated heart rate (92 beats/min). We established maternal and fetal cardiac monitoring. Routine medical management of an acute myocardial infarction was then performed. Using pelvic examination, we exposed effective uterine contractions and a 4-cm cervical dilatation with 70% effacement. Fetal well-being parameters [non-stress text (NST), fetal estimated weight, biophysics profile] were normal. Continuous fetal and maternal monitoring were performed during the whole peripartum period, and 4 h after admission a 2900-g, healthy male infant was delivered via a normal vaginal delivery without any complications. A work-up was performed in order to find the etiology of the myocardial infarction after delivery. An echocardiography, which was undertaken on the same day of admission, revealed septal hypokinesia and a small aneurysm at the apex. No sign of valvular heart disease was obtained. One day later, a coronary artery angiography was undertaken and showed a proximal spiral-shaped left anterior descending artery (LAD) dissection (Fig. 1). A perfusion defect was found but as no sign of ischemia was found in the thallium-201 syntigraphy, which was performed 1 week after the coronary artery angiography, no intervention was considered necessary. Spiral-shaped dissection of the left anterior descending artery (black arrow) The patient was symptom free and discharged on the 12th day of her admission with her healthy baby. Acute myocardial infarction during the antepartum period is a rare phenomenon and complicates approximately 1 per 10 000 deliveries and causes an increase in both maternal and fetal mortality of up to 50%. From the first case described by Katz in 1922, up to 1996, 125 well-documented cases whose ages range from 16 to 45 have been presented in the literature (3, 4). According to this study, primary coronary artery dissection as a reason for acute myocardial infarction was seen in only three cases among the antepartum group and eight cases in the postpartum group. According to our medical literature review, there are 14 reported cases of coronary artery dissection during the antepartum period, including our case 5-16). Patient characteristics, risk factors, clinical course, treatment modalities and mode of the delivery were determined. The mean age of the cases was 33.1 (range: 22–44), and the mean gravida and parity were 2.0 (range: 1–5) and 0.9 (range: 0–3), respectively. The 24-year-old patient, in our case, was the youngest patient in the literature. The earliest gestational age reported was 9 weeks; the pregnancy resulted in maternal death (11). The mean gestational age was 33 weeks (range: 9–40). In only two cases (14%) did the patients have risk factors for coronary artery disease; one (7%) had hypertension, the other one (7%) was a smoker. LAD was involved in 11 (78%) patients, whereas the left circumflex artery (LCx) was involved in seven (50%) patients. Only LAD involvement, which was determined in 50% of all the patients, was the most common location of dissection. The involvement of more than one vessel was seen in six (42%) patients (Table I). Anterior wall myocardial infarction (AWMI), which occurred in six (42%) patients, was the most common type of myocardial infarction (Table II). Out of all the patients, four (29%) died (6, 11, 15). Two pregnant women of 40 and 9 weeks gestation died along with their fetuses. Two healthy babies were delivered from another two died women by emergency cesarean sections (6, 15). Maternal and fetal mortality were determined as 29% and 7% (excluding the 9 week pregnant patient), respectively. Because of hemodynamic instability, three (21%) patients had emergency coronary artery bypass surgery (grafting) and the remaining patients were treated with medical therapy until their delivery time. The initial treatment of coronary artery dissection should probably consist of heparin, nitro-glycerin and immediate catheterization. Choice of treatment mostly depends on the result of the angiography. According to literature many of the non-pregnant patients suffering from coronary artery dissection were treated with thrombolysis (33% of all cases) (17). Thrombolytic therapy should be performed very carefully as on the one hand the thrombolytic treatment may resolve the thrombus in the false lumen and improve the flow in the true lumen; on the other hand thrombolysis may aggravate the bleeding and the dissection. Although thrombolytic agents have been used in pregnancy for deep venous thrombosis and pulmonary embolism (18), their usage for coronary artery dissection in pregnancy is not recommended due to the increased risk of maternal and fetal hemorrhage. Among the cases we reviewed, thrombolytic therapy was not used. Therapeutic modalities concerning the non-medical treatment of women with spontaneous coronary artery dissection are not clearly defined. Coronary bypass surgery, percutaneous transluminal coronary angioplasty (PTCA) and coronary artery stenting are used for treatment (19, 20). Some authors think that PTCA could be applied to dissection, as it has a limited extension of up to 1 cm and causes less than 50% narrowing of the lumen. A coronary artery must be stented after PTCA to prevent extension and recurrence of the dissection. However, some authors believe that coronary bypass surgery with or without a cardiopulmonary bypass is the most preferred surgical treatment of coronary artery dissection even in pregnant women who do not have contraindication for anesthesia and surgery (21). Except for our case, all the patients were delivered by cesarean sections. We do not exactly know the indications for cesarean sections in these patients, but our case was delivered via a normal vaginal delivery. Concerning the type of delivery there is not enough data in the literature. All of the patients, except for ours, had no history of any medication during the time of dissection. In the case we presented, the patient had being using oral ritodrine for preterm labor for 1 week before the onset of dissection. During pregnancy, the increment of heart rate and blood volume makes the heart require more oxygen. Because our case had no risk factors, her use of oral ritodrine seems to have further increased the demand for oxygen of her heart with its positive inotropic effect and predispose the coronary artery dissection. In the literature, there are no primary coronary artery dissection cases associated with ritodrine usage among pregnant and non-pregnant patients. Because acute myocardial infarction is rare among young people, the possibility of intrinsic coronary artery dissection must be considered when a pregnant woman presents with signs of a myocardial infarction. Address for correspondence: Ali Ayhan Department of Obstetrics and Gynecology Ankara Turkey e-mail: esinler@hacettepe.edu.tr