A multidifferentiator-based approach to the reliable determination of T-wave offset in electrocardiograms

Initial and terminal T wave angle as hyperkalemia indicator in chronic kidney disease

BACKGROUND

Hyperkalemia is one prevalent complication in chronic kidney disease and is considered fatal since it potentially causes malignant arrhythmias and mortality. It is associated with electrocardiography (ECG) changes, such as peaked T wave in all ECG leads. However, the universal definition of the peaked T wave is still unclear, with low sensitivity and specificity.

AIM

: This study aims to determine the predictive value of initial and terminal T wave angle in detecting hyperkalemia among CKD patients.

METHODS

: A cross-sectional study was conducted at Dr. Soetomo General Hospital, including all adult hospitalized CKD patients. A caliper was used to measure T wave morphology. The initial deflection angle (Tia) and terminal deflection angle (Tta) were calculated from an arctan of T peak amplitude and the respective initial or terminal length. The receiver operating characteristics (ROC) curve was analyzed to determine the area under the curve (AUC) and optimal cut-off.

RESULTS

: A total of 220 CKD patients were enrolled in this study, with 98 patients with hyperkalemia (potassium >5.0). The majority of the patients were male, with a mean age of 51.12±12.58 years. Ti-Tp duration, Tp-Tt duration, Tia, Tta, and Tp amplitude were significantly higher in the hyperkalemia group (all p<0.05). A Spearman correlation analysis demonstrated a significant positive correlation of Tia (r=0.346 and p<0.001) and Tta (r=0.445 and p<0.001) with potassium levels in the participants. The optimal cut-off angle for Tta was 66.20^o (sensitivity=67.3% and specificity=73.8%) and Tia was 61.07^o (sensitivity=66.3% and specificity=69.7%).

CONCLUSION

: The terminal T wave angle outperformed the initial angle in predicting hyperkalemia in CKD patients.

Prevalence and prognostic significance of long QT interval in patients with acute coronary syndrome: review of the literature

BACKGROUND

Sympathetic hyperactivity is linked with several adverse cardiovascular events in patients with acute coronary syndrome (ACS). Sympathetic activity increases early in the process of ischemia through 2 mechanisms. One originates from the central nervous system and leads to enhanced sympathetic activity. The other mechanism originates at the infarct zone and leads to B receptor up-regulation and catecholamine supersensitivity. Nevertheless, sympathetic hyperactivity accompanied by an underlying myocardial structural damage is likely to increase the ventricular repolarization duration measured as QT interval on the body surface electrocardiogram.

PURPOSE

The aims of the current review of the literature were to examine the physiological processes underlying the use of long QT interval as a risk prediction tool in patients with ACS and to critically review and critique the existing evidence related to this matter.

CONCLUSION

The available evidence is contradictory and includes serious limitations in design and QT measurement and correction. Until accurate and reliable data are available, it is difficult to determine the additional clinical value and prognostic significance of long QT interval in patients with ACS beyond that in other patients.

CLINICAL IMPLICATIONS

Long QT interval is not uncommon among patients with ACS. Automated continuous QT interval monitoring is superior to manual QT interval measurement with the standard 10-second electrocardiogram. Optimum care for patients with ACS requires nurses to keep monitoring the QT interval several days after the initial event.

Comparative TQT analysis with three fully-automated platforms: comparison to core laboratory semi-automated results

BACKGROUND AND PURPOSE

Technological advances in machine-read QT measurement now enable detailed and precise cardiac repolarization assessments. This study assessed the applicability of three state-of-art ECG measurement applications to provide reliable continuous analyses from data obtained in a positive thorough QT study previously characterized with sparse semi-automated measurements performed by an ECG core laboratory.

METHODS

Continuous RR, QT, QTc measurements, and individual QT/RR relationships and their associated intra- and inter-subject variability were derived in parallel with BioQT, Ponemah PRO, and WinAtrec analysis software.

RESULTS

Despite slight vendor-specific differences in measurement variability and QTc, all machine-read methods demonstrated requisite assay sensitivity and yielded similar conclusions in accordance with SA analysis.

CONCLUSIONS

Three commercially available ECG analytical software applications reliably detected the drug-induced QT prolonging effects and replicated the SA core-laboratory conclusions, with greatly improved temporal resolution and reduced analytical costs. With broader experience, these data suggest that current SA methodologies could be effectively replaced by fully automated ECG analysis.