Left atrial size is an independent predictor of overall survival in patients with primary systemic amyloidosis.

BACKGROUND: Primary systemic amyloidosis is a severe plasma cell disorder characterized by the extracellular deposition of amyloid fibrils in different organs. Echocardiography is usually performed to assess cardiac involvement. We hypothesized that in patients with systemic amyloidosis, simple echocardiographic measurement of the left atrial (LA) diameter indexed to the body surface area might provide an important risk marker for this disease.

METHODS: Between 1997 and 2011, 134 patients were diagnosed with primary systemic amyloidosis and had echocardiography within 28 days; we collected their baseline characteristics and biological and echocardiographic data retrospectively. LA enlargement was defined as recommended as M-mode LA diameter greater or equal to 23 mm/m(2).

RESULTS: One hundred and eleven patients (83%) had echocardiographic LA dimension data available (mean age 63±11 years; 61% men; 31% previously diagnosed with systemic hypertension). Mean left ventricular ejection fraction (LVEF) and interventricular septum thickness (IVST) were 62±12% and 14±4 mm, respectively. Mean follow-up was 2.8±2.9 years (maximum 12 years). Patients with LA enlargement had a slightly lower LVEF (P=0.08) and a significantly greater IVST (P<0.0001). Overall, 5-year survival was 57±5%. However, 1-year and 5-year survival rates were markedly reduced in patients with LA enlargement versus those without LA enlargement (61±7% and 39±8% vs 83±5% and 72±7%, respectively; P=0.0007). On multivariable analysis, after adjusting for age, sex, LVEF, IVST, presence of hypertension and creatinine concentration, LA enlargement remained an independent predictor of overall mortality at 5 years (hazard ratio 2.47; 95% confidence interval 1.11-5.90; P=0.02).

CONCLUSION: LA enlargement, a surrogate marker of diastolic dysfunction, is an independent predictor of long-term mortality and may therefore help to enhance risk stratification and management of patients presenting with amyloidosis.