Sheena Bohonis

Obstructive Sleep Apnea : Effects of Continuous Positive Airway Pressure on Cardiac Remodeling as Assessed by Cardiac Biomarkers, Echocardiography, and Cardiac MRI

BACKGROUND Obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular morbidity and mortality. Although previous echocardiographic studies have demonstrated short-term improvement in cardiovascular remodeling in patients with OSA receiving continuous positive airway pressure (CPAP) therapy, a long-term study incorporating cardiac biomarkers, echocardiography, and cardiac MRI (CMR) has not been performed to date. METHODS A prospective study of 47 patients with OSA was performed between 2007 and 2010. Cardiac biomarkers, including C-reactive protein (CRP), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and troponin T (TnT), were measured at baseline and serially over 1 year. All patients underwent baseline and serial transthoracic echocardiography (TTE) and CMR to assess cardiac remodeling. RESULTS Following 12 months of CPAP therapy, levels of CRP, NT-proBNP, and TnT did not change significantly from normal baseline values. As early as 3 months after initiation of CPAP, TTE revealed an improvement in right ventricular end-diastolic diameter, left atrial volume index, right atrial volume index, and degree of pulmonary hypertension, which continued to improve over 1 year of follow-up. Finally, left ventricular mass, as determined by CMR, decreased from 159 ± 12 g/m(2) to 141 ± 8 g/m(2) as early as 6 months into CPAP therapy and continued to improve until completion of the study at 1 year. CONCLUSION Both systolic and diastolic abnormalities in patients with OSA can be reversed as early as 3 months into CPAP therapy, with progressive improvement in cardiovascular remodeling over 1 year as assessed by both TTE and CMR.

Multimodality Imaging of Aortic Dimensions: Comparison of Transthoracic Echocardiography with Multidetector Row Computed Tomography

Background: With recent advances in multimodality cardiac imaging, a number of methods exist for the noninvasive assessment of aortic disease. Although multidetector row computed tomography (MDCT) remains the gold standard for aortic measurements, there are a number of limitations including radiation and contrast‐induced nephropathy. Transthoracic echocardiography (TTE) is an alternative to MDCT for providing accurate anatomic assessment of aortic root and ascending aorta dimensions. Objectives and Methods: To determine the accuracy of two‐dimensional (2D) TTE for determining aortic measurements in comparison to MDCT, a retrospective study of individuals with varying aortic root and ascending aorta dimensions was performed. Results: There were 116 patients (77 males, mean age 49 ± 12 years) in total. The maximum aortic diameters by 2D TTE were 26.1 ± 4.3 mm (annulus), 32.4 ± 5.6 mm (sinuses), 30.1 ± 5.9 mm (sinotubular [ST] junction), and 33.4 ± 7.3 mm (ascending aorta). The maximum aortic diameters by MDCT were 30.1 ± 4.1 mm (annulus), 35.8 ± 5.8 mm (sinuses), 33.2 ± 5.9 mm (ST junction), and 37.4 ± 7.6 mm (ascending aorta). There was good to excellent correlation between 2D TTE and MDCT at all four levels of the aorta (annulus: r = 0.84; sinuses: r = 0.93; ST junction: r = 0.93; ascending aorta: r = 0.88). There was a consistent underestimation of aortic measurements obtained by 2D TTE when compared to MDCT. Conclusion: 2DTTE is a feasible, accurate, and reproducible method for the noninvasive assessment of thoracic aortic diameters as compared to MDCT. (Echocardiography 2012;29:735‐741)

The utility of dobutamine stress echocardiography for the diagnosis of coronary artery disease in the HIV population.

Background: The introduction of highly active antiretroviral therapy (HAART) has increased human immunodeficiency virus (HIV) patient longevity by 10–15 years. This increased longevity has habituated new cardiovascular complications, in particular, accelerated coronary artery disease (CAD). Although dobutamine stress echocardiography (DSE) is a highly sensitive and specific test for the noninvasive detection of underlying CAD in the general population, its utility in the HIV population remains unknown. Objective: The objective of the current study was to assess the validity of DSE for the noninvasive detection of underlying symptomatic CAD in the HIV population using cardiac catheterization as the gold standard. Methods and results: A total of 40 HIV positive patients (mean 49 ± 8 years; 31 males) between 2006 and 2009 inclusively underwent routine DSE and coronary angiography. A positive stress echo with new wall motion abnormalities was detected in 9 (23%) individuals. Coronary angiography, following DSE, detected obstructive CAD in 12 (30%) individuals. For the diagnosis of obstructive CAD, DSE has a sensitivity of 67%, specificity of 97%, positive predictive value (PPV) of 89%, and negative predictive value (NPV) of 87%. Conclusion: In this select HIV population, DSE was highly specific for the noninvasive detection of obstructive CAD. (Echocardiography 2010;27:1228‐1232)

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

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?

An unusual presentation of left ventricular free wall rupture

Left ventricular free wall rupture (LVFWR) is one of the most lethal complications following myocardial infarction. It accounts for approximately 12% to 21% of all in-hospital deaths following myocardial infarction. The majority of patients die shortly after LVFWR from instantaneous pericardial tamponade and hemodynamic collapse. However, up to one-third of cases are subacute in nature, allowing limited time for emergent surgical repair to prevent sudden death. A high index of suspicion and timely use of diagnostic tests are important in recognizing cases. The present report describes the case of a 69-year-old man who initially presented with acute pericardial tamponade and was subsequently diagnosed with LVFWR in the operating room as the cause of his hemopericardium. The pathology, diagnosis and management of LVFWR are reviewed.