The first change takes place in ECG in hyperkalemia is

(A) Tall T wave # Effects of Hyperkalemia on the ECG:> Serum potassium > 5.5 mEq/L is associated with repolarization abnormalities:> Peaked T waves (usually the earliest sign of Hyperkalaemia)> Vital for assessing the physiologic significance of the hyperkalemia> ECG findings generally correlate with the potassium level, but potentially life-threatening arrhythmias can occur without warning at almost any level of hyperkalemia> In patients with organic heart disease and an abnormal baseline ECG, bradycardia may be the only new ECG abnormality> ECG changes have a sequential progression, which roughly correlate with the potassium level> Early ECG changes of hyperkalemia, typically seen at a serum potassium level of 5.5-6.5 mEq/L, include the following:> Tall, peaked T waves with a narrow base, best seen in precordial leads> Shortened QT interval> ST-segment depression> At a serum potassium level of 6.5-8.0 mEq/L, the ECG typically shows the following: Peaked T waves Prolonged PR interval Decreased or disappearing P wave Widening of the QRS Amplified R wave> At a serum potassium level higher than 8.0 mEq/L, the ECG shows the following: Absence of P wave Progressive QRS widening Intraventricular/fascicular/bundle branch blocks> Progressively widened QRS eventually merges with the T wave, forming a sine wave pattern. Ventricular fibrillation or asystole follows.