Natural history of thromboembolism in AL amyloidosis.

To determine the natural history of thromboembolism in patients with biopsy-proven AL amyloidosis, medical records of 2,132 patients evaluated at Mayo Clinic between 1975 and 2000 were reviewed. Forty patients (21 male) were found to have objectively documented thromboembolism. The median age was 65 years. Four patients had a monoclonal gammopathy of undetermined significance, 20 had an unspecified plasma cell proliferative disorder, 11 had multiple myeloma, and 1 had Waldenström macroglobulinemia. Twelve patients had cardiac amyloid, and 20 had renal amyloid. Neither the extent of the amyloid nor the type of monoclonal protein was predictive of the development of thromboembolic events. Thromboembolism preceded the diagnosis of AL amyloidosis in 11 patients, occurred at the time of diagnosis or within 1 month after diagnosis in 11 patients, and occurred 1 month or more after diagnosis in 18 patients. Twenty-nine patients (73%) had venous thrombosis and 11 (28%) had arterial thrombosis. Eight patients (20%) died within 1 month after the thrombotic event, and 18 (45%) died within 1 year. The development of thrombosis in patients with AL amyloidosis appears to predict significant mortality within the first month and year after the event.