Echocardiographic indices of left ventricular function and filling pressure are not related to blood pool activity on pyrophosphate scintigraphy

J Nucl Cardiol. 2023 Apr;30(2):708-715. doi: 10.1007/s12350-022-02989-4. Epub 2022 May 16.


Background: Pyrophosphate (PYP) imaging has a high diagnostic accuracy for transthyretin cardiac amyloidosis (ATTR-CA). Indeterminate findings are often reported due to persistent blood pool activity, presumed to be from low cardiac output. We evaluated the relationship between blood pool activity on PYP imaging and echocardiographic indices of cardiac function.

Methods: Clinical and imaging data of 189 patients referred for PYP scintigraphy were evaluated. All patients underwent planar imaging and SPECT (diagnostic standard). Among those with a negative PYP SPECT, persistent left ventricular blood pool activity on planar images was inferred by a visual score ≥2 or a heart-to-contralateral (HCL) ratio ≥ 1.5. Absence of blood pool activity was inferred when both visual score was < 2 and HCL was < 1.5. Left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), stroke volume index (SVi), and left atrial pressure (LAP) were calculated from standard transthoracic echocardiograms.

Results: ATTR-CA was present in 43 (23%) patients. Among those with a negative PYP SPECT, 11 patients had significant blood pool activity. Patients with ATTR-CA had a lower LVEF, SVi, and GLS, with a higher LAP, compared to those without ATTR-CA. Among those without ATTR-CA, there were no significant differences in these parameters.

Conclusion: Approximately 8% of patients with a negative PYP SPECT have significant blood pool activity. Measures of cardiac function are not different among those with and without blood pool activity. PYP SPECT should be routinely performed in all patients to avoid false image interpretation.

Keywords: Amyloid heart disease; Echo; SPECT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid Neuropathies, Familial* / diagnostic imaging
  • Cardiomyopathies* / diagnostic imaging
  • Diphosphates
  • Echocardiography
  • Humans
  • Prealbumin
  • Radionuclide Imaging
  • Radiopharmaceuticals
  • Stroke Volume
  • Technetium Tc 99m Pyrophosphate
  • Ventricular Function, Left


  • diphosphoric acid
  • Diphosphates
  • Technetium Tc 99m Pyrophosphate
  • Radiopharmaceuticals
  • Prealbumin