Principal component analysis of the T wave: 24 hour monitoring of repolarization complexity in dialysis patients

The 24-hour changes in the complexity of ventricular repolarization in hemodialysis (HD) patients were quantified by principal component analysis (PCA) of the T wave. The effects of dialysis sessions leading to different plasma potassium levels (´Ktow´ and ´Khigh´) were analyzed. Forty-six Hotter recordings were collected from twelve patients. PCA was applied to the T waves extracted from each beat. Repolarization complexity was quantified by the ratio of the second to the first eigenvalue (PCA ratio). Hemodialysis caused a significant increase in the PCA ratio (+50% at the end of the sessions), which recovered to the basal value during the first hour post-dialysis. In the last two hours of dialysis PCA ratio was significantly higher in Klow sessions than in Khigh ones. Results show a significant HD-induced increase of the T wave complexity, strongly related to the therapy-induced potassium depletion.