673 Effects of Normal Pregnancy on Cardiovascular Remodeling as Assessed by Echocardiography and Cardiac Magnetic Resonance Imaging: Insights From the CHIRP Study

Abstract

BACKGROUND: Cardiovascular disease in pregnancy is the most common non-obstetric cause of increased maternal morbidity and mortality in North America. Currently, the most commonly used noninvasive imaging modality for the characterization of cardiovascular remodeling in the peripartum period involves the use of transthoracic echocardiography (TTE). There have been no previous studies describing the role of cardiac MRI (CMR) in assessing cardiac structure and function during normal healthy pregnancies and in the postpartum period. OBJECTIVE: The objective of the CHIRP (Cardiac hemodynamic imaging and remodeling in pregnancy) study was to compare TTE and CMR in the non-invasive assessment of cardiovascular remodeling in the peripartum period. METHODS: Eligible study subjects were between the ages of 18 and 35, carrying a singleton pregnancy. All women underwent TTE and CMR (Figure 1) at two time points: initially during their third trimester, and again at least three months postpartum. Postpartum imaging was performed as a surrogate for the baseline (non-pregnant) cardiovascular state, for comparison with third trimester data. RESULTS: A total of 20 healthy pregnant women were prospectively enrolled at a single tertiary care centre between 20102012 (mean age 28 4 years). Third trimester imaging took place at a mean gestational age of 33 2 weeks, and postpartum imaging took place an average of 14 2 weeks after delivery. Although there was no evidence of left ventricular hypertrophy during pregnancy using TTE, there was an increase in LV mass using CMR. Using TTE, there was an increase in stroke volume (SV) from 48 14 mL to 70 15 mL (p 0.05), combined with a concurrent increase in heart rate, resulting in an increase in mean cardiac output (CO) from 3.2 0.9 L/min at baseline to 5.1 1.4 L/min in the third trimester (p 0.05). Although CO increased from 3.3 0.2 L/min to 5.4 0.3 L/min using CMR as well, the tighter confidence intervals reflect the greater precision of CMR in the non-invasive assessment of cardiac remodeling. There was no change in LV systolic or diastolic functional parameters during the study period using either TTE or CMR. CONCLUSION: As compared to traditional TTE, CMR was able to detect changes in LV mass and cardiac output with more accuracy. Once normal reference values for cardiac dimensions and function are established by the CHIRP study, we will be able to evaluate the utility of CMR in the management of maternal cardiac disease states, including congenital heart disease, peripartum cardiomyopathy, and pulmonary hypertension in the near future. Figure 1. 674 CAN CORONARY COMPUTED TOMOGRAPHY ANGIOGRAPHY ENHANCE OUR UNDERSTANDING OF CORONARY ARTERY DISEASE IN THE SOUTH ASIAN POPULATION?