Published in:
23-02-2023 | Heart Failure | BRIEF REPORT
Diagnostic performance characteristics of planar quantitative and semi-quantitative parameters of Tc99m pyrophosphate (PYP) imaging for diagnosis of transthyretin (ATTR) cardiac amyloidosis: the SCAN-MP study
Authors:
Shivda Pandey, MBBS, FASNC, Sergio Teruya, MD, Carlos Rodriguez, Albert Deluca, MD, Mona Kinkhabwala, MD, Lynne L. Johnson, MD, Denise Fine, MS, Natalia Sabogal, Morgan Winburn, Michelle Castillo, Ketan Bhatia, Rita Malkovskaya, Farbod Raiszadeh, MD, PhD, Damian Kurian, MD, Edward J. Miller, MD, PhD, Andrew J. Einstein, MD, PhD, MASNC, Mathew S. Maurer, MD, Frederick L. Ruberg, MD
Published in:
Journal of Nuclear Cardiology
|
Issue 4/2023
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Abstract
Background
The optimal heart-to-contralateral chest (H/CL) ratio threshold for non-invasive diagnosis of transthyretin cardiac amyloidosis (ATTR-CA) using Tc99m pyrophosphate (PYP) imaging in a population with low pretest probability is not known.
Methods
Using myocardial PYP retention by SPECT as the reference standard, we evaluated the diagnostic performance of different semi-quantitative and quantitative (H/CL chest ratio) planar parameters obtained from 3-hour PYP imaging in a prospectively recruited cohort of minority older adults with heart failure and increased LV wall thickness.
Results
Of 229 patients, 14 were found to have ATTR-CA (6.1%). No PYP uptake (grade 0) was observed in 77% of scans, all grade 3 scans were ATTR-CA, and only 4 of 11 (36%) grade 2 scans were ATTR-CA. An H/CL threshold of ≥ 1.4 maximized specificity (99%) and positive predictive value (93%) but resulted in decreased sensitivity (93%), compared to the ≥ 1.3 threshold which had 100% sensitivity.
Conclusion
Among patients with a low pretest likelihood of ATTR-CA, planar interpretation, while useful to exclude disease, must be interpreted with caution. H/CL ratio threshold of ≥ 1.3 resulted in clinically important misclassifications. These data suggest that quantitative planar imaging thresholds may not be appropriate to apply in low pretest likelihood populations being evaluated for ATTR-CA.