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. Author manuscript; available in PMC: 2014 Jul 1.
Published in final edited form as: J Electrocardiol. 2013 Apr 15;46(4):336–342. doi: 10.1016/j.jelectrocard.2013.03.007

Table 4.

Time duration, prevalence of long mean QTc interval, and QTc > 500 ms burden using different QTc formulas.

QTc formula Mean QTc (ms) Long Mean QTc [Male / Female] QTc > 500 ms Burden (%)
Mean ± SD (range) n, % Mean ± SD (range)
Bazett 447.31 ± 30.26 (381.56 to 550.98) 19 (13.1%) [7 (4.8%) / 12 (8.3%)] 8.22 ± 20.66 (0.00 to 99.80)
Fridericia 438.23 ± 29.37 (386.79 to 548.08) 14 (9.7%) [6 (4.1%) / 8 (5.5%)] 4.77 ± 16.92 (0.00 to 99.80)
Framingham 436.50 ± 28.37 (384.42 to 547.00) 13 (9%) [5 (3.4%) / 8 (5.5%)] 4.08 ± 16.11 (0.00 to 99.80)
Study specific (log) 433.69 ± 30.90 (369.25 to 546.60) 14 (9.7%) [6 (4.1%) / 8 (5.5%)] 4.28 ± 16.21 (0.00 to 99.60)
Study specific (linear) 433.45 ± 29.72 (374.19 to 546.10) 13 (9%) [5 (3.4%) / 8 (5.5%)] 3.83 ± 15.60 (0.00 to 99.40)
Subject specific (log) 435.66 ± 33.74 (373.10 to 553.26) 17 (11.7%) [8 (5.5%) / 9 (6.2%)] 5.16 ± 19.12 (0.00 to 99.80)
Subject specific (linear) 436.61 ± 33.33 (372.02 to 555.83) 17 (11.7%) [8 (5.5%) / 9 (6.2%)] 5.09 ± 19.11 (0.00 to 99.7)

linear, linear QT/RR regression line pattern; log, logarithmic QT/RR regression line pattern; ms, millisecond; QTc, QT interval corrected for heart rate; SD, standard deviation.