Background: Cycle-dependent variation of myocardial integrated backscatter (CV-IB) is an objective measurement that may detect myocardial abnormalities. However, no data exist about the prognostic value of CV-IB in primary cardiac amyloidosis.
Methods and results: We prospectively examined 208 consecutive biopsy-proven patients with primary amyloidosis. The magnitude of CV-IB was analyzed at the interventricular septum and left ventricular (LV) posterior wall and its prognostic value was compared with standard Doppler measurements with to the Tei index (isovolumic contraction time plus isovolumic relaxation time divided by ejection time). One hundred thirty-three patients had cardiac involvement (mean LV thickness > 12 mm). Forty-one patients (20%) (32 cardiac deaths) died during a mean follow-up of period of 307+/-156 days. Univariate analysis showed that the CV-IB at the LV posterior wall was the best predictor of cardiac death (P<0.0001) and all-cause death (P< 0.0001). The Tei index did not identify patients at risk of death. Multivariate analysis showed that CV-IB at the LV posterior wall was the only independent predictor of both cardiac and overall deaths.
Conclusions: Among patients with cardiac amyloidosis, CV-IB at the LV posterior wall is a powerful predictor of clinical outcome and is superior to standard echocardiographic/Doppler flow indexes.