Abstract 14334: Best Electrocardiographic Criteria for Hyperkalemia in Chronic Hemodialysis Patients

Abstract

Introduction: To date, the effects of hyperkalemia (HK) on the ECG in chronic hemodialysis (HD) patients are inconsistent. No studies examining all of the possible effects of HK on the ECG of HD patients have been performed. We studied the ECGs of 128 consecutive HD patients with acutely clotted grafts or fistulas. ECGs from 46 HK patients with potassium levels ≥5.5 mEq/L were compared to 82 patients with normal potassium (NK) levels < 5.5 mEq/L. Methods: Patients with bundle branch block or cardiac events within 3 months were excluded. There were no differences between HK & NK patients for dialysis duration, causes of ESRD, cardiac disease or serum levels of Na + , Ca 2+ , HCO3, or phosphorus. ECG analysis included: height & width of P waves, T waves in V4 & Lead II, time intervals of PR, QRS, QT, QTc, PR/QT, PR/QTc & slopes of ascending & descending T waves in Lead II & V4. For the first time ever in HK HD patients, the ECG measurements in 32 HK patients were compared to their own NK ECGs obtained 3 to 6 months from the HK event. Results: Univariate analysis between the 46 HK & 82 NK patients showed 4 differences in mean values: V4 T wave height 4.0 vs 2.9mm, Lead II T wave height 2.7 vs. 2.0 mm, & V4 T wave ascending (.03 vs .02) & descending slopes (.04 vs .03). Multivariate analysis for all clinical & ECG findings between HK & NK patients found only the increased height of the T wave in V4 was significant, p<0.05. In contrast, the ECG analysis of the HK patients to their NK ECGs revealed more differences: higher T wave height in V4 (5.0 vs 3.7mm), higher T wave height in Lead II (4.0 vs 2.7 mm), shorter width of T wave in V4 (2.4 vs 4.1ms) & Lead II (2.1 vs 4.1ms), longer PR (188 vs 167ms) & steeper slopes in the T waves in Leads II & V4. Regression analysis of the change in potassium from NK to HK to each ECG measurement above showed that the only significant correlation was to the width (r= -.433, p= .007) & height (r= .333, p=.03) of the T wave in V4. In these HK HD patients T wave tenting in V4 was present in 56%. Conclusion: Intra-patient comparison of baseline NK to HK ECGs in HD patients confirms the importance of the height of the T wave in Lead V4 to diagnose HK. Shortened width and increased height of T waves in V4 are the most predictive ECG changes of HK.