Cardiac Amyloidosis in Spinal Stenosis: the CASS-study

Background: A significant portion of cardiac amyloidosis patients have a 5 to 10 years prior history of spinal canal stenosis, reflecting a diagnostic red flag that should raise suspicion for amyloidosis presence. Mild troponin release and NT-proBNP elevation, both serum cardiac biomarkers, often coincide with cardiac amyloidosis. Early cardiac amyloidosis treatment improves survival, warranting timely diagnosis. Study aim: to test a prospective screening strategy, based on serum cardiac biomarkers, to increase early detection of cardiac amyloidosis in patients with spinal canal stenosis. Design: Single-centre prospective observational non-interventional diagnostic study. Methods: Consecutive patients during a one-year period in AZ Sint-Jan Bruges, without known cardiac amyloidosis history and scheduled for spinal canal stenosis surgery, will have cardiac evaluation including serum cardiac biomarker (high-sensitive troponin T and NT-proBNP) assessment, electrocardiography and transthoracic echocardiography. During surgery, all patients will undergo ligamentum flavum biopsy to evaluate presence and burden of transthyretin amyloid deposition (Congo-red staining and immune histochemistry). All patients with suspicion for cardiac amyloidosis will undergo further diagnostic testing (including laboratory test and bone scintigraphy). A chronologic cascade screening process will be used starting with abnormal serum cardiac biomarkers (high-sensitive troponin T ≥ 14 ng/ml and/or NT-proBNP \> 125 pg/ml), followed by electrocardiography, transthoracic echocardiography and finally ligamentum flavum biopsy results. The diagnostic performance of this biomarker-based strategy will be compared to electrocardiography, echocardiography and ligamentum flavum biopsy. Conclusion: It is hypothesised that serum cardiac biomarker testing in patients undergoing spinal canal stenosis surgery represents a simple and valuable prospective screening strategy for early detection of cardiac am