All of the following are the electrocardiographic features of severe hyperkalemia, EXCEPT:

U waves in ECG are seen in cases of hypokalemia. ECG changes in hyperkalemia according to increasing levels of serum potassium are: (mEq/L) ECG Changes 6.5-7.5 Prolonged PR interval, tall peaked T waves, sho QT interval 7.5-8.0 Flattening of the P wave, QRS widening 10-12 QRS complex degradation into a sinusoidal pattern Ref: Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7rd Edition, Chapter 21 ; Tarascon Pediatric Emergency Pocketbook By Dr. Rothrock, Page 65