Table 1.

Diagnostic characteristics of 11 Ftc formulae

	Thresh.	Sens.	Spec.	Conc.	R2
Mechanical Equations
FtcWodey = systolic time + 0.00129 (HR − 60) 20	2%	96%	93%	100%	0.75
FtcWeissler = systolic time + 0.0016 (HR − 60) 11	3%	91%	93%	98%	0.71
FtcGobbato = systolic time + 0.00192 (HR − 60) 18	3%	91%	93%	95%	0.66
FtcPenati = systolic time + 0.00122 (HR − 60) 19	2%	93%	93%	99%	0.75
FtcLian = cycle time [0.709 x systolic time x (cycle time + 0.41)] 26	4%	78%	87%	89%	0.61
Electrical Equations
${\mathit{Ftc}}_{\mathit{\text{Bazett}}}=\frac{\mathit{\text{systolic\hspace{0.17em}time}}}{\sqrt{\mathit{\text{cycle}}}\mathit{\text{time}}}$24	3%	91%	93%	98%	0.71
${\mathit{Ftc}}_{\mathit{\text{Fredericia}}}=\frac{\mathit{\text{systolic\hspace{0.17em}time}}}{\sqrt[3]{\mathit{\text{cycle}}}\mathit{\text{time}}}$25	2%	87%	85%	90%	0.55
FtcHodges = systolic time + 0.00175 (HR − 60) 16	3%	91%	93%	97%	0.68
FtcFramingham = systolic time + 0.154 (1.0 − cycle time) 21	2%	93%	93%	98%	0.73
FtcAdams = systolic time + 0.1464 (1.0 − cycle time) 22	2%	93%	93%	98%	0.74
FtcChambers = systolic time + 0.127 (1.0 − cycle time) 23	2%	96%	93%	99%	0.76

Thresh. represents optimal threshold change in corrected flow time. Sens. is sensitivity (%) and spec. is specificity (%) for detecting a 10% change in stroke volume. Conc. is concordance rate (%) and R² is the regression coefficient from the four-quadrant plot