Table 4. Diagnostic performance of selected ECG findings in the recognition of reduced left ventricular ejection fraction (<0.50) in T.cruzi seropositive blood donors.

ECG variable	Sensitivity	Specificity	Positive predictive value	Negative predictive value
Abnormal ECG	92 (76–98)	45 (40–50)	12 (8–16)	99 (96–100)
Wide QRS (> = 120 ms)	47 (30–64)	83 (79–97)	18 (11–28)	95 (93–97)
Prolonged QTc (>440 ms)	56 (38–72)	79 (75–82)	17 (11–25)	96 (93–97)

Data is presented as median (interquartile range) * Reported if <0.05** HRV data available in 24 seropositive subjects with LVEF<0.50 and 433 with LVEF> = 0.50. seropositive and 458 seronegative subjects. QTc: corrected QT interval by Bazett's formula; HRV: heart rate variability; rmssd: root mean square of successive differences in normal RR intervals; sdnn: standard deviation of all normal RR intervals.