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Proximal Aorta Longitudinal Strain in Marfan Syndrome
Study Questions:
Do proximal aorta longitudinal and circumferential strain assessed on cardiac magnetic resonance (CMR) imaging predict aortic root dilation rate and aortic events among patients with Marfan syndrome?
Methods:
A cohort of 117 patients with Marfan syndrome, less than moderate aortic regurgitation, and no previous aortic dissection or cardiac/aortic surgery were prospectively included in a multicenter protocol. At baseline, CMR was performed and proximal aorta longitudinal strain and ascending aorta circumferential strain and distensibility were assessed. Ascending aorta maximal (Amax) and minimal cross-sectional areas (Amin) were measured, and brachial systolic (BPs) and diastolic blood pressure (BPd) were assessed immediately after the CMR. Ascending aortic distensibility was calculated as (Amax – Amin)/Amin/(BPs – BPd). Using maximum (Dmax) and minimal aortic diameters (Dmin) and an assumption that aortas were circular in cross section, circumferential strain was calculated as (Dmax – Dmin)/Dmin. Longitudinal strain was computed using tracking software. All patients were treated with either atenolol or losartan and followed clinically at 6-month intervals. CMR was repeated at the end of the study. Aortic events were taken to be aortic dissection or rupture, or a guideline-based indication for aortic surgery.
Results:
During follow-up (85.7 [75.0-93.2] months), the annual growth rate of the aortic root diameter was 0.62 ± 0.65 mm/year. Fifteen patients underwent elective surgical aortic root replacement and four experienced an aortic dissection. After correcting for baseline clinical and demographic characteristics and aortic root diameter, proximal aorta longitudinal strain, but not circumferential strain or distensibility, was an independent predictor of the aortic root diameter growth rate (p = 0.001, p = 0.823, and p = 0.997, respectively), z-score growth rate (p = 0.013, p = 0.672, and p = 0.680, respectively), and aortic events (p = 0.023, p = 0.096, and p = 0.237, respectively).
Conclusions:
Among patients with Marfan syndrome, proximal aorta longitudinal strain was independently related to aortic root dilation rate and clinical aortic events.
Perspective:
Current guidelines recommend the use of aortic diameter as a predictor of complications and as a threshold for prophylactic surgery among patients with Marfan syndrome. This study found that CMR-derived proximal aorta longitudinal strain was associated with the rate of aortic expansion and with clinical aortic events. If these findings are confirmed in larger trials, then the assessment of proximal aorta longitudinal strain may in the future play a role in identifying patients with Marfan syndrome who are at higher risk, and help guide the timing of aortic intervention.
Clinical Topics: Cardiac Surgery, Congenital Heart Disease and Pediatric Cardiology, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Valvular Heart Disease, Vascular Medicine, Aortic Surgery, Cardiac Surgery and Arrhythmias, Cardiac Surgery and CHD and Pediatrics, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Imaging, CHD and Pediatrics and Interventions, CHD and Pediatrics and Prevention, Interventions and Imaging, Interventions and Structural Heart Disease, Interventions and Vascular Medicine, Magnetic Resonance Imaging
Keywords: Aneurysm, Dissecting, Aortic Valve Insufficiency, Atenolol, Blood Pressure, Cardiac Surgical Procedures, Diagnostic Imaging, Dilatation, Heart Defects, Congenital, Losartan, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Marfan Syndrome, Secondary Prevention, Systole, Vascular Diseases
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