The increasing burden of amyloidosis from apex to base: new insights from technetium-99m pyrophosphate imaging
Ray S, Aahad K, Hussaini S, et al. The Increasing Burden Of Amyloidosis From Apex To Base: New Insights From Technetium-99M Pyrophosphate Imaging. Journal of the American College of Cardiology. 2017;69(11):1521. doi:10.1016/s0735-1097(17)34910-0.
Session Title: Nuclear Cardiology: Beyond Perfusion Location: American College of Cardiology 66th Annual Scientific Session Saturday, March 18, 2017, 9:45 a.m.-10:30 a.m. Abstract Category: 30. Non Invasive Imaging: Nuclear Presentation Number: 1196-202 Poster Contributions, Poster Hall, Hall C
BACKGROUND: Two-dimensional speckle-tracking strain echocardiography (2D STE) in cardiac amyloidosis (CA) patients has shown relatively preserved left ventricle apical systolic function as measured by longitudinal strain (LS). Technetium-99m pyrophosphate ( 99mTc-PYP) myocardial imaging has gained favor in diagnosis of transthyretin amyloidosis. Since 99mTc-PYP binds amyloid fibrils, we hypothesized this technique can elucidate relative distribution of amyloid in the heart.
METHODS: We identified 9 patients with CA diagnosis who had had 2D STE and 9mTc-PYP scans. Segmental LS was measured by 2D STE as a measure of systolic function. Segmental uptake of 99mTc-PYP was measured using a 17-segment model as a measure of CA burden in the specific segment. If uptake was 100% of maximum, it was categorized as 0% defect.
Results: Mean LS was markedly decreased in CA patients (-8.3) and much lower in normal patients. Strain increased from base to apex on 2D STE (average basal strain [-3.3] vs. mid strain [-8.3] vs. apical strain [-14]); p<0.01 for all comparisons. Percent defect increased gradually from base to mid to apex (10%, 38%, 60% defect, respectively) in CA patients; p<0.0001 for all comparisons. Apical cap percent defect was not significant from apex (48.7 vs 59.5; p=0.7547).
CONCLUSIONS: These data provide the first insight into relative distribution of amyloid in the ventricle and suggest the relative apical sparing of systolic strain may be a function of amyloid deposition of the ventricular base.