Perfusion defects on thallium-201 scintigraphy in cardiac amyloidosis

Thallium-201 scintigraphy can detect microvascular diseases; however, the correlation between cardiac amyloidosis and thallium-201 scintigraphy findings is unknown. We aimed to investigate the influence of amyloid deposition on thallium-201 scintigraphy. We retrospectively analyzed individuals with cardiac amyloidosis at National Taiwan University Hospital, reviewing baseline characteristics, biochemistry, echocardiography, thallium-201 scintigraphy, and coronary angiography. Thirty-six participants were enrolled, of whom 32 had transthyretin amyloid cardiomyopathy. The left ventricular (LV) posterior wall thickness was 13.71 ± 2.45 mm, and the summed stress score (SSS) and summed difference score (SDS) on thallium-201 scintigraphy were 5.47 ± 6.42 and 2.16 ± 2.13, respectively. Abnormal thallium-201 scintigraphy findings were observed in 72.22% of patients. In Spearman's correlation analysis, both the SSS and summed difference score (SDS) were significantly correlated with LV posterior wall thickness (SSS: r = 0.43, p = 0.008; SDS: r = 0.50, p = 0.002). In multivariable analysis, LV posterior wall thickness remained the only significant predictor of SSS (β = 0.410, 95% CI: 0.250-1.895, p = 0.012). Coronary angiography was performed in eight of the patients with abnormal thallium-201 scintigraphy, none of whom had physiologically significant coronary artery lesions. Abnormal thallium-201 scintigraphy findings were common in the patients with cardiac amyloidosis, even though they did not have significant epicardial coronary lesions. Furthermore, SSS was associated with LV posterior wall thickness. These results suggest that thallium-201 scintigraphy may help identify myocardial perfusion abnormalities related to cardiac amyloidosis, particularly in patients presenting with unexplained LV hypertrophy and nonobstructive coronary arteries.