Oral Abstract 3: Ascending Aortic Graft Replacement Alters Left Ventricular Performance – Novel Insights Enabled by Cine-CMR Myocardial Strain Quantification

Presenting Author(s)

• NN

  Nupoor Narula, MD, MSc

  Assistant Professor of Medicine
  Weill Cornell Medicine

Primary Author(s)

• NN

  Nupoor Narula, MD, MSc

  Assistant Professor of Medicine
  Weill Cornell Medicine

Co-Author(s)

• PV

  Pablo Villar-Calle, MD

  Instructor in Medicine
  Weill Cornell Medicine
• MR

  Mahniz Reza, BA

  Research Assistant
  Weill Cornell Medicine
• RA

  Rachel Axman, MD

  Resident, Internal Medicine
  Weill Cornell Medicine
• LJ

  Lily Jin, BSc

  Research Coordinator
  Weill Cornell Medicine
• RZ

  Robert S. Zhang, MD

  Instructor in Medicine
  Weill Cornell Medicine
• MR

  Mary Roman, MD

  Professor of Medicine
  Weill Cornell Medicine
• RD

  Richard C. Devereux, MD

  Professor of Medicine
  Weill Cornell Medical College
• 

  Jiwon Kim, MD

  Associate Professor of Medicine
  Weill Cornell Medicine
• JH

  Jay Humphrey, PhD

  Professor of Biomedical Engineering
  Yale University
• AR

  Alberto Redaelli, PhD

  Professor
  Politecnico di Milano, Italy
• YW

  Yadong Wang, PhD

  McAdam Family Foundation Professor of Heart Assist Technology
  Cornell University
• CL

  Christopher Lau, MD

  Associate Professor of Cardiothoracic Surgery
  Weill Cornell Medicine
• MG

  Mario Gaudino, MD, PhD

  Professor
  Weill Cornell Medicine
• LG

  Leonard N. Girardi, MD

  O. Wayne Isom Professor and Chairman
  Weill Cornell Medicine
• 

  Jonathan W. Weinsaft, MD

  Chief of Cardiology, Professor of Medicine
  Weill Cornell Medicine

Background: Surgical graft replacement of the ascending thoracic aorta is widely performed in patients with thoracic aortic aneurysms (TAA), for whom it produces lifesaving benefits including elimination of dissection risk in graft-replaced regions. However, current prosthetic grafts are stiffer than native aortic tissue and thus hold the potential to alter left ventricular (LV) loading conditions. Cardiac MRI (CMR) provides a powerful tool to assess cardiac biomechanics, but has yet to be used to assess impact of surgical prosthetic graft replacement on LV and left atrial (LA) performance.  


Methods: CMR was prospectively performed pre- (within 6 months) and post- (target 6 months) operatively among TAA patients undergoing elective surgical (Dacron) prosthetic graft implantation; clinical data were used to classify TAA etiology (bicuspid [BAV] vs. non-bicuspid aortopathies). CMR (3T) included functional (cine), flow (phase velocity), and LGE enhancement tissue characterization. Cine-CMR was acquired via a conventional SSFP pulse sequence (typical TR/TE: ~3.8/1.5msec, flip angle: ~55°, temporal resolution: ~50msec) and used to test impact of grafts on cardiac performance via conventional chamber planimetry and longitudinal LV (2-, 3-, 4-) and LA (4-chamber) global longitudinal strain (GLS) as measured with a tailored feature tracking algorithm for which endocardial seed points were tracked throughout the cardiac cycle.


Results: 27 patients (85% M; 58±11yo) with TAA (30% BAV) were studied using CMR performed pre- (0.54±0.60) and post- (5.67±2.44 months) proximal aortic graft replacement. Cardiac volumetric indices, blood pressure, and heart rate were all similar between time points (Table), and LGE was uniformly absent. Despite this, LV (21.3±2.7% vs. 20.2±2.8%; p=0.01) and LA (22.2±5.2% vs. 19.7±4.6%; p< 0.001) GLS decreased after grafting: Impaired LV and LA GLS persisted (both p< 0.05) even after exclusion of patients with advanced pre-operative aortic regurgitation. Subgroup analysis demonstrated significant decrements in LA GLS (a marker of diastolic function) in BAV and non-BAV TAA patients (both p< 0.05; Figure). Significant reductions in LV GLS (a marker of systolic function) were also seen in BAV patients (p=0.049), with a similar trend among non-BAV aortopathies (p=0.11) (Figure).


Conclusion: Cine-CMR strain quantification provides additional utility over conventional cine-CMR (volumetric) analysis to identify altered myocardial performance after proximal aortic graft replacement. Both LV and LA longitudinal strain decrease after grafting, suggesting that grafts impair systolic and diastolic performance independent of significant aortic valve dysfunction. Further studies are warranted to test if short-term strain impairments persist or progress, and if CMR-evidenced strain impairments after graft surgery impact prognosis.

Pre- and Post-Operative LV and LA Strain by Etiology