Spinal amyloid deposits are common among older patients undergoing spinal stenosis decompression surgery

Background

Recent advances in the management of transthyretin amyloid cardiomyopathy (ATTR-CM) have highlighted the need for early identification. Studies have demonstrated amyloid deposits in orthopedic surgical specimens, prompting a diagnosis of concurrent ATTR-CM. We sought to determine the prevalence of spinal amyloid deposits among patients undergoing spinal stenosis decompression surgery and whether the presence of deposits was associated with ATTR-CM.

Methods

Patients >60 years of age undergoing spinal stenosis decompression surgery were enrolled as part of a prospective, single-center, cohort study. Samples from the disc and ligamentum flavum were obtained during surgery. Patients with amyloid deposition on Congo red staining returned for standard-of-care clinical assessment consisting of blood testing, a transthoracic echocardiogram, nuclear pyrophosphate imaging when indicated, and an evaluation with a cardiologist.

Results

Out of 54 enrolled patients, 24 patients (44%; 95% CI, 31%–59%) were found to have spinal amyloid deposits. Amyloid-positive patients were older than amyloid-negative patients (70 years vs. 63 years, p < 0.01). On follow-up testing, no amyloid-positive patients were found to have definitive ATTR-CM. However, 37% of amyloid-positive patients had abnormal cardiac biomarkers, and 36% of amyloid-positive patients had reduced global longitudinal strain on echocardiography, suggesting possible early disease.

Conclusions

Spinal amyloid deposits, in both the disc and ligamentum flavum, were found in 44% of older patients undergoing spinal stenosis decompression surgery. While none of these patients tested positive for ATTR-CM on early follow-up, subtle abnormalities in cardiac testing suggest that further follow-up testing is warranted to detect the advent of cardiac amyloidosis in the future.