PMC4774943_01
Twelve-lead standard electrocardiogram before administration of dronedarone.
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It should be noted that, during sinus rhythm, the ECG was normal showing an unremarkable QRS morphology and a QRS duration of 85 msec (Fig. 1).
Left bundle branch block pattern after two doses of dronedarone.
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In the index patient, after two doses of dronedarone (400 mg each), a marked prolongation of QRS duration with a left bundle branch block pattern was documented on the 12-lead ECG (Fig. 2).
Return to normal QRS-width after dronedarone withdrawal and self-limiting episode of atrial fibrillation.
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On the following day, the QRS complexes again showed a normal morphology and a normal duration of 90 msec (Fig. 3).