The American journal of cardiology
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Several formulas have been proposed to adjust the QT interval for heart rate, the most commonly used being the QT correction formula (QTc = QT/square root of RR) proposed in 1920 by Bazett. The QTc formula was derived from observations in only 39 young subjects. Recently, the adequacy of Bazett's formula has been questioned. ⋯ The linear regression model yielded a correction formula (for a reference RR interval of 1 second): QTLC = QT + 0.154 (1-RR) that applies for men and women. This equation corrects QT more reliably than the Bazett's formula, which overcorrects the QT interval at fast heart rates and undercorrects it at low heart rates. Lower and upper limits of normal QT values in relation to RR were generated.(ABSTRACT TRUNCATED AT 250 WORDS)