Figure 3.

The effects of exposure to higher altitudes in patients using placebo (1860 and 2590 m, respectively) versus 490 m are illustrated by plotting median differences with 95% confidence interval (CI) of the corresponding mean QTc intervals during entire nights (meanQTc, panel A1), mean QTc intervals during minutes with the highest values of the nights (maxQTc, panel A2), and the QT dispersion (panel A3). The effects of acetazolamide vs. placebo at 1860 and 2590 m on meanQTc, maxQTc, and QT dispersion are illustrated in a similar way in panels B1-B3. MeanQTc, maxQTc and QT dispersion were prolonged at the higher altitudes and acetazolamide prevented the altitude induced increase in meanQTc and in QT dispersion.