Lamarre-Cliche et al. (A-15) state, “The QT interval corrected for heart rate (QTc) is believed to reflect sympathovagal balance. It has also been established that b-blockers influence the autonomic nervous system.” The researchers performed correlation analysis to measure the association between QTc interval, heart rate, heart rate change, and therapeutic blood pressure response for 73 hypertensive subjects taking b-blockers. The researchers found that QTc interval length, pretreatment heart rate, and heart rate change with therapy were not good predictors of blood pressure response to b1-selective b-blockers in hypertensive subjects.