26. 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
Age (X) BP (Y) Age (X) BP (Y)
470 CHAPTER 9 SIMPLE LINEAR REGRESSION AND CORRELATIONhypertensive 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.