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 amyloid(osis).

Inclusion Criteria:

• Cervical or lumbar spinal canal stenosis, scheduled for spinal surgery
• > 18 years old

Exclusion Criteria:

Prior diagnosis of cardiac amyloidosis and evident alternative explanations for troponin and/or NT-proBNP elevation are the main reasons for exclusion.

• known cardiac amyloidosis
• severe valvular regurgitation or stenosis
• Left ventricular ejection fraction (LVEF) < 40%
• Glomerular filtration rate (GFR) ≤ 25 ml/kg/min or dialysis
• recent heart failure admission ≤ 1 month
• recent myocarditis ≤ 3 months
• recent acute coronary syndrome ≤ 1 month
• recent percutaneous coronary intervention (PCI) ≤ 1 month
• recent cardiac surgery ≤ 3 months
• active or planned pregnancy
• unwilling to participate or provide signed informed consent

Patients with cervical or lumbar spinal canal stenosis scheduled for spinal surgery