This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Electrocardiography, Subject name: Medicine
Initial ECG change in Hyperkalemia is? 
Select and explain. 
A. Tall tented T waves, B. PR prolongation, C. qRS widening, D. ST segment depression
A: Tall tented T waves
Answer: A: Tall tented T waves 
Explanation: Ans.(a) Tall tented T wavesRef: Harrison 19th ed. / 310Serum potassium > 5.5 mEq/L is associated with repolarization abnormalities:* Peaked T waves (usually the earliest sign of hyperkalemia) Serum potassium >6.5 mEq/L is associated with progressive paralysis of the atria:* P wave widens and flattens* PR segment lengthens* P waves eventually disappearSerum potassium >7.0 mEq/L is associated with conduction abnormalities and bradycardia:# Prolonged QRS interval with bizarre QRS morphology# High-grade AV block with slow junctional and ventricular escape rhythms* Any kind of conduction block (bundle branch blocks, fascicular blocks)* Sinus bradycardia or slow AF* Development of a sine wave appearance (a pre-terminal rhythm)Serum potassium level of > 9.0 mEq/L causes cardiac arrest due to:* Asystole* Ventricular fibrillation