Evaluating cardiac electrophysiological markers for predicting arrhythmic risk in hypothyroid patients
Sibel Tunç Karaman1, Abdullah Ozan Polat1, Okcan Basat1
1Gaziosmanpaşa Training and Research Hospital, Department of Family Medicine, University of Health Sciences, Istanbul, Turkey.
Insights
Hypothyroidism increases arrhythmia risk, detectable through ECG parameters like iCEB. Differentiating subclinical and overt hypothyroidism aids risk management, with iCEB proving most effective for identifying arrhythmic risk.
Area of Science:
- Cardiology
- Endocrinology
- Medical Diagnostics
Background:
- Hypothyroidism is a condition affecting thyroid hormone levels, potentially influencing cardiac electrophysiology.
- Levothyroxine (LT4) is the standard treatment for hypothyroidism, but its impact on cardiac electrical stability requires further investigation.
- Electrocardiogram (ECG) parameters offer insights into cardiac electrical activity and can be used to assess arrhythmia risk.
Purpose of the Study:
- To evaluate the impact of hypothyroidism and levothyroxine (LT4) treatment on cardiac arrhythmic risk.
- To analyze multiple ECG parameters, including the Index of Cardio-Electrophysiological Balance (iCEB), frontal QRS-T angle, Tp-e/QT ratio, and QT dispersion (QTd).
- To determine the most effective ECG parameter for identifying arrhythmia risk in hypothyroid patients.
Main Methods:
- A cross-sectional study involving 132 adult patients with primary hypothyroidism on LT4 treatment and 132 matched healthy controls.
- Thyroid function tests and comprehensive ECG measurements were performed on all participants.
- The hypothyroid group was stratified based on thyroid-stimulating hormone (TSH) levels into subclinical and overt hypothyroidism.
Main Results:
- Hypothyroid patients exhibited significantly higher Tp-e/QT ratios, iCEB, median frontal QRS-T angles, and corrected QT dispersion (cQTd) compared to controls.
- Patients with overt hypothyroidism showed elevated Tp-e/QT ratios, iCEB, and median frontal QRS-T angles.
- Logistic regression identified a higher iCEB score as a significant predictor of arrhythmia risk (AUC 0.70), with high sensitivity (0.80).
Conclusions:
- Patients with hypothyroidism possess an elevated risk of developing arrhythmias.
- ECG parameters such as Tp-e interval, iCEB, frontal QRS-T angle, and QTd are crucial for assessing this risk.
- The Index of Cardio-Electrophysiological Balance (iCEB) demonstrates the highest efficacy in detecting arrhythmic risk in hypothyroid individuals.
Objectives:
This study aimed to evaluate the impact of hypothyroidism and levothyroxine (LT4) treatment on arrhythmic risk by concurrently analyzing multiple electrocardiogram (ECG) parameters such as the Index of Cardio-Electrophysiological Balance (iCEB), frontal QRS-T angle, Tpeak-Tend (Tp-e) interval/QT interval ratio, and QT dispersion (QTd).
Methods:
This cross-sectional study included 132 adult patients with primary hypothyroidism who had been receiving LT4 treatment, and 132 demographically matched healthy controls. The hypothyroid group was also stratified by thyroid-stimulating hormone (TSH) levels (subclinical <4.5 and overt ≥ 4.5). Participants underwent a series of thyroid function and ECG measurements.
Results:
The hypothyroid and healthy control groups were matched for age and gender (p = 0.080; p = 0.176). Participants with hypothyroidism had higher Tp-e/QT ratios, iCEB, median frontal QRS-T angle, and corrected QT dispersion (cQTd) than healthy controls (p = 0.004; p = 0.025; p = 0.004; p = 0.004, respectively). In the overt group, the Tp-e/QT ratio, iCEB, and median frontal QRS-T angles were all higher (p = 0.012, p = 0.037, and p = 0.016, respectively). Logistic regression analysis indicated that a higher iCEB score (β = 0.60, p = 0.003) was significant for the detection of arrhythmia risk. ROC analysis showed that iCEB had the highest sensitivity (0.80), moderate specificity (0.60), and AUC 0.70.
Conclusion:
Patients with hypothyroidism have a higher risk of arrhythmia. To assess this risk, it is important to analyze the Tp-e interval, iCEB, frontal QRS-T angle, and QTd. Differentiating between patients with subclinical and overt hypothyroidism can help minimize the risk of arrhythmia. iCEB is the most effective method for identifying arrhythmic risk. Using all these parameters can improve the accuracy of arrhythmic risk detection in patients with hypothyroidism.
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