T wave morphology changes during hemodialysis

Risk stratification for sudden cardiac death in hemodialysis (HD) patients is an unmet clinical need. Non invasive electrophysiological testing is challenging in these patients due to their oscillating cardiovascular and electrolyte status induced by the intermittent HD treatment. We hypothesized that continuous electrocardiographic monitoring during their regular HD session can provide reproducible repolarisation profiles.

Continuous 12-lead digital electrocardiographs (ECGs) were recorded during dialysis in stable patients and were repeated at two-week intervals for 5 times. QRS-to-T angle (TCRT), principal component analysis (PCA) ratio and T wave morphology dispersion (TMD) were calculated every 5s in overlapping 10-s ECG segments. Serum electrolytes and plasma parathyroid hormone (PTH) levels were measured prior to the first recording.

There were 319 acceptable recordings from 76 hemodialysed patients. Repeated Measures Anova showed intra-subject reproducibility of all descriptors. Mean PCA ratio and TMD values increased through dialysis and their intradialytic change correlated with heart rate changes (r = 0.305, p = 0.007 and r = 0.287, p = 0.012, respectively). TCRT showed a variable response to HD and the intradialytic change correlated positively with PTH levels (r = 0.284, p = 0.023).

Repolarisation descriptors demonstrate subject-specific dynamic profiles during HD. PTH has a role in dynamics of myocardial repolarisation. The potential clinical utility of continuous intradialytic ECGs for risk stratification purposes should be prospectively evaluated.