Erin Faherty1, Hari Rajagopal2, Simon Lee3, Barry Love4, Shubhika Srivastava5, Ira A Parness2, Santosh C Uppu6
1 Department of Pediatric Cardiology, Yale New Haven Children's Hospital, New Haven, CT, USA
2 Department of Pediatric Cardiology, Steven and Alexandra Cohen Children's Medical Center, New York, NY, USA
3 Department of Pediatric Cardiology, Nationwide Children's, Columbus, OH, USA
4 Department of Pediatric Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
5 Department of Pediatric Cardiology, Nemours Children's Health System, Wilmington, DE, USA
6 Department of Pediatric Cardiology, Children's Heart Institute, UTHealth Houston, McGovern Medical School, Houston, TX, USA
Background : Transthoracic echocardiographic (TTE) estimation of the pulmonary to systemic flow ratio (Qp/Qs) is routinely used in clinical practice and is included in the American Society of Echocardiography Guidelines. We sought to assess its real-world applicability with a particular focus on hemodynamically significant shunt lesions.
Methods : Retrospective single institutional review of TTE's in patients with secundum atrial septal defect prior to cardiac catheterization (cath) from 2012 to 2018 was performed (n = 109), those with technically limited images for Qp/Qs calculation (n = 11) and those with time interval between TTE and cath >60 days were excluded (n = 14). Qp/Qs was calculated from stored clips by previously described methods and correlated with those obtained by oximetry. Patients were subdivided into two age groups <21 (Group 1) and ≥22 years (Group 2). TTE and cath methods for Qp/Qs estimation were compared using paired t-test, Pearson's correlation coefficient, and Bland–Altman plots.
Results : Eighty-four subjects met inclusion criteria (age range 3–78 years). Group 1 n = 35; median age 10 years; Group 2 n = 49; median age 49 years. Transthoracic echocardiogram was performed 19.5 ± 15 days prior to cath. Mean Qp/Qs derived by cath and TTE were 2.09 ± 0.9 versus 2.54 ± 1.2 (P < 0.0001). Overall correlation was poor between the methods (r2 = 0.32, P < 0.0001) and continued to be poor for Groups 1 and 2 (r2 = 0.24, P = 0.003 and r2 = 0.40, P < 0.0001 respectively). Bland–Altman plots demonstrated poor agreement between the predetermined limits of agreement (-0.5–1.5).
Conclusion : Transthoracic echocardiography estimated Qp/Qs, although routinely utilized in clinical practice, has poor correlation and agreement with oximetry-derived Qp/Qs. The test performs poorly in all age groups in detecting a hemodynamically significant shunt and tends to overestimate the degree of left to right shunt.
Dr. Santosh C Uppu
6410, Fannin Street, Suite 425 Houston, Tx 77030
Source of Support: None, Conflict of Interest: None
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