Sex-related differences in testing and diagnostic thresholds usingTechnetium-99m pyrophosphate imaging in the evaluation of transthyretin cardiac amyloidosis
C Deluca, S Babbar, J Nunes, C Akincioglu, N Fine, D Juneau, R M Iwanochko, D Delgado, T D Ruddy, G R Small, M Pelletier-Galarneau, G Wells, R J H Miller, N AleksovaAbstract
Background
Technetium-99m pyrophosphate (Tc-PYP) imaging is increasingly used to detect transthyretin cardiac amyloidosis (ATTR-CA). Current research suggests that ATTR-CA is more commonly diagnosed in males than females. However, this sex-related discrepancy is poorly understood and may be related to differences in clinical suspicion, testing thresholds as well as diagnostic thresholds with Tc-PYP imaging in females compared to males.
Purpose
This study aimed to explore the sex-related disparities of Tc-PYP imaging results for patients with suspected ATTR-CA using the Canadian Cardiac Amyloidosis Pyrophosphate Imaging Registry (CAPER).
Methods
We conducted a retrospective analysis of patients in CAPER, a multi-centre national registry, who received a Tc-PYP scan from 2016-2023. Tc-PYP imaging from all study centres included planar and SPECT images. Categorical variables were compared using χ2 or Fisher exact test where appropriate, while continuous variables were compared with t-test or Wilcoxon rank sum tests as appropriate. All tests were two-sided and a p-value < 0.05 was considered significant.
Results
There were 2118 patients with Tc-PYP imaging: 1452 males (69%) and 666 females (31%). 32% of males (n=460) and 24% of females (n=158) had confirmed ATTR-CA (Table 1). Female patients were significantly more likely to undergo Tc-PYP imaging and have a pre-existing diagnosis of heart failure (HF) compared to males (37% vs 27%, p<0.01). Females with ATTR-CA were more likely to have a diagnosis of HF and a diagnosis of atrial fibrillation compared to females without ATTR-CA (p=0.004 and p<0.001, respectively). In patients with ATTR-CA, planar visual grades of the Tc-PYP scan (0 to 3) were significantly different between males and females (p=0.003) (Table 2). Specifically, there were fewer females (62.4%) with planar visual grade 3 than males (76.7%). Additionally, the heart/contralateral lung (H/CL) ratio was significantly lower in females than males (1.685 vs. 1.800, p<0.001). SPECT classifications (Normal/Equivocal/Abnormal) were not significantly different between males and females with ATTR-CA (p=0.95). Comparing planar visual grades and SPECT classifications in patients with ATTR-CA, the total distribution of planar grades differed markedly between males and females, with a total variation of 26.8%, while SPECT classifications showed only 0.4% variation.
Conclusions
Our study finds that a diagnosis of HF was more common in females than males undergoing PYP imaging and HF was more common in females with ATTR-CA than females without ATTR-CA. Tc-PYP imaging in females with ATTR-CA have significantly fewer planar visual grade 3 and lower H/CL ratio than males with ATTR-CA, while SPECT classification is not significantly different between the sexes. Our results support the importance of SPECT in Tc-PYP imaging, especially in the diagnosis of female patients with suspected ATTR-CA.For image description, please refer to the figure legend and surrounding text.For image description, please refer to the figure legend and surrounding text.