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. 2016 Mar 8;67(9):1053–1058. doi: 10.1016/j.jacc.2015.12.033

Figure 3.

Figure 3

Effect of Mexiletine in 2 LQT3 Patients

Upper panels (Patient A) show the effect of mexiletine in a child with a baseline QTc of 500 ms who had a syncope at the age of 1 year during fever. After starting mexiletine, his QTc shortened to 468 ms and he has remained asymptomatic for 2 years.

The lower panels (Patient B) show the effect of mexiletine in a girl with a baseline QTc of 542 ms who experienced recurrent syncopal events while receiving nadolol. On mexiletine, the QTc shortened to 427 ms and she remained asymptomatic for 7 years.

The beats used to measure the electrocardiographic parameters before and after starting mexiletine are indicated by the dotted lines (black for the RR interval, red for the QT interval).