Tei et al developed an index based on Doppler echocardiographic findings for evaluating a patient with cardiac amyloidosis. This correlates with overall survival for the patient. The authors are from the Mayo Clinic.
Parameters:
(1) interval between the end of one mitral inflow period and the onset of the next period in msec
(2) ejection time of the left ventricle in msec
Doppler Index =
= ((interval in msec between the end and onset of mitral inflow) - (ejection time of the left ventricle in msec)) / (ejection time of the left ventricle in msec)
interval between the end of one mitral inflow period and the onset of the next in msec =
= (ICT) + (ejection time of the left ventricle) + (IRT)
where:
• ICT = isovolumetric contraction time
• IRT = isovolumetric relaxation time
Interpretation:
• The normal index is < 0.41.
• In cardiac amyloidosis the index is increased.
Doppler Index
Overall Survival at 2 Years
Overall Survival at 3 Years
<= 0.77
60%
40%
> 0.77
25%
10%
from Figure 6, page 663
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