Longitudinal Precedes Circumferential Strain Abnormality in Sickle Cell Anemia: A Cardiovascular Magnetic Resonance Feature-Tracking Study

Author: Hannah Jacobs, DO, Additional Authors^**

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Background
Sickle Cell Disease (SCD) is an autosomal recessive hemolytic disease that affects 1 in 360 African American live births. Sickle cell anemia (SCA) is the most common variant of SCD leading to chronic transfusions.   Chronic transfusions result in iron overload and deposition of iron in the heart and liver leading to diastolic dysfunction. Systolic dysfunction with decline in global function as assessed by ejection fraction is a late finding. Studies in non-ischemic cardiomyopathy (NICMD) demonstrate incremental predictive values of additional strain parameters over left ventricular ejection fraction (LVEF) to predict cardiovascular events. Prior transthoracic echocardiography (TTE) studies demonstrate abnormal global longitudinal strain (GLS) in SCA patients, an indicator of early occult cardiac dysfunction. We hypothesized that both GLS and GCS are abnormal (≥ -17) compared to controls and that GLS decline precedes that of GCS in patients with SCA with preserved LVEF.

Objective
To quantify myocardial deformation from cine cardiac magnetic resonance (CMR) images using Feature-Tracking (FT) based technique in patients with SCA compared healthy control subjects.

Methods
Single institution retrospective study of SCA patients and control subjects with CMR evaluation. GLS and GCS were obtained from three long axis views and three short axis views using a commercially available CMR-FT software (Medis Medcal Imaging, Qstrain 3.2, Leiden, Netherlands). Demographic and clinical CMR data including LVEF was collected for statistical analysis using Student’s T-test.

Results
28 SCA patients were identified with complete CMR dataset (age 16.1±4.9 years) and 11 age-matched control subjects (age 18.5±0.7 years, p = 0.06). Indexed LV end diastolic volume (LVEDVI) was larger in SCA patients compared to control (109.2±18.2 vs 96.8±14.1, p = 0.03) with no difference in LVEF (59.3±5.6% vs 58.4±5.7%, p = 0.3). SCA patients had lower GLS and GCS magnitude (GLS -14.8±2.8 vs -20.3±1.5, p < 0.0001 and GCS -17±3.6 vs -20.1±1.5, p = 0.004) compared to control. There were no difference between GLS and GCS in control subjects but GLS magnitude was significantly lower than GCS in patients with SCA (-14.8±2.8 vs -17±3.6, 0.009).

Conclusion
Our study confirmed prior studies that GLS is abnormal compared to control group but also found that GCS magnitude was significantly lower compared to control. In addition, we found that GLS decline precedes GCS decline in SCA patients with preserved LVEF. The use of multiple strain parameters have been shown to have incremental predictive value in NICMD to predict cardiovascular events. This may suggest that using CMR-FT to evaluate myocardial strain can be used as an early diagnostic tool to assess for occult dysfunction and perhaps lead to earlier intervention to decrease cardiovascular events. Future larger longitudinal studies are needed to determine rate of progression and patient outcomes.

See references in poster.

**Additional Authors:

Hannah Jacobs, DO, Nationwide Children’s Hospital, Columbus, OH
Simon Lee, MD, Nationwide Children’s Hospital, Columbus, OH
Corey Stiver, MD, Nationwide Children’s Hospital, Columbus, OH
Jason Williams, MD, Nationwide Children’s Hospital, Columbus, OH
Susan Creary, MD, Nationwide Children’s Hospital, Columbus, OH
Anthony Villella, MD, Nationwide Children’s Hospital, Columbus, OH
Marc Lee, MD, Nationwide Children’s Hospital, Columbus, OH
Kan Hor, MD, Nationwide Children’s Hospital, Columbus, OH