The Relationship between P & QT Dispersions and Presence & Severity of Stable Coronary Artery Disease

Effect of thyrotropin suppressive therapy on heart rate variability and QT dispersion in patients with differentiated thyroid cancer

The effects of thyrotropin (TSH) suppressive therapy on autonomic regulation and ventricular repolarization in patients with differentiated thyroid cancer (DTC) have not been elucidated. The aim of present study was to evaluate variation in heart rate variability (HRV) and QT dispersion after TSH suppressive therapy in patients with DTC.Cases, defined as 271 patients with DTC within 1 year of exogenous levothyroxine, and all patients underwent a full history, physical examination, including standard 12 lead electrocardiogram (ECG), and 24 h ambulatory ECG monitoring (Holter) with normal free thyroxine (FT4) and free triiodothyronine (FT3) with levothyroxine. To evaluate effects of TSH suppressive therapy on HRV and QT dispersion, patients were divided into three groups according to different levels of TSH: TSH < 0.1 mIU/L group and 0.1 ≤ TSH < 0.5 mIU/L group were as TSH suppression groups, and 0.5 ≤ TSH < 2.0 mIU/L group was as TSH replacement group.Comparing with 0.5 ≤ TSH < 2.0 mIU/L group, significant changes in both time and frequency domain of HRV and QT dispersion were observed in TSH < 0.1 mIU/L group (P < .001: SDNN, SDANN, HF, LF/HF, QTd, and QTcd; P < .05: rMSSD) and 0.1 ≤ TSH < 0.5 mIU/L group (P < .001: SDNN, HF, LF/HF, QTd, and QTcd), and especially were more pronounced in TSH < 0.1 mIU/L group. Moreover, we found that TSH level was proportional to SDNN (β = 15.829, P < .001), but inversely proportional to LF/HF (β = -0.671, P < .001), QTd (β = -16.674, P < .001) and QTcd (β = -18.314, P < .001) in DTC patients with exogenous levothyroxine.Compared with euthyroid state, patients with suppressed serum TSH have increased sympathetic activity in the presence of diminished vagal tone, ultimately showed sympathovagal imbalance and with an increased inhomogeneity of ventricular recovery times. These findings revealed that TSH suppression therapy had a significant impact on cardiovascular system and had certain guiding role in the treatment and management of patients with DTC.

Electrocardiographic predictors of cardiovascular events in patients at high cardiovascular risk: a multicenter study

BACKGROUND

There are limited data on the prevalence of electrocardiographic (ECG) abnormalities, and their value for predicting a major adverse cardiovascular event (MACE) in patients at high cardiovascular risk. This study aimed to determine the prevalence of ECG abnormalities in patients at high risk for cardiovascular events, and to identify ECG abnormalities that significantly predict MACE.

METHODS

Patients aged ≥ 45 years with established atherosclerotic disease (EAD) were consecutively enrolled from the outpatient clinics of the six participating hospitals during April 2011 to March 2014. The following data were collected: demographic data, cardiovascular risk factors, history of cardiovascular event, physical examination, ECG and medications. ECG was analyzed using Minnesota Code criteria. MACE included cardiovascular death, non-fatal myocardial infarction, and hospitalization due to unstable angina or heart failure.

RESULTS

A total of 2009 patients were included, 1048 patients (52.2%) had established EAD, and 961 patients (47.8%) had multiple risk factors (MRF). ECG abnormalities included atrial fibrillation (6.7%), premature ventricular contraction (5.4%), pathological Q-wave (Q/QS) (21.3%), T-wave inversion (20.0%), intraventricular ventricular conduction delay (IVCD) (7.3%), left ventricular hypertrophy (LVH) (12.2%), and AV block (12.5%). MACE occurred in 88 patients (4.4%). Independent predictors of MACE were chronic kidney disease, EAD, and the presence of atrial fibrillation, Q/QS, IVCD or LVH by ECG.

CONCLUSIONS

A high prevalence of ECG abnormalities was found. The prevalence of ECG abnormalities was high even among those with risk factors without documented cardiovascular disease.

Are P Wave and QT Dispersions Related to Severe Peripheral Artery Disease?

Background

The aim of this study was to evaluate the relationship between P wave and QT dispersions (PWD and QTD) during the course of severe peripheral artery disease (PAD).

Material/Methods

We recruited 163 patients who underwent peripheral angiography (PA) between August 2011 and March 2017, and they were divided into 2 groups according to the severity of PAD on PA. PWD and QTD were investigated using 12-lead electrocardiograms. Group One consisted of patients diagnosed with <70% stenosis on PA, who eventually received medical treatment; Group Two consisted of patients diagnosed with ≥70% stenosis on PA, who eventually underwent surgery.

Results

ROC curve analysis of the 2 groups demonstrated that PWD was significantly higher in Group Two (AUC: 0.913505; 95% confidence interval (CI): 0.859365 to 0.951788; p<0.0001). The Youden index showed that a cut-off PWD value of >35 msn predicted a peripheral artery stenosis of ≥70% with a sensitivity of 88.89% and a specificity of 85.37% (+LR: 6.07, −LR: 0.13). Moreover, QTD was significantly higher in Group Two (AUC: 0.884749; 95% CI: 0.825489 to 0.929391; p<0.0001). Youden index showed that a cut-off QTD value of >75 msn predicted a peripheral artery stenosis of ≥70% with a sensitivity of 76.54% and a specificity of 85.37% (+LR: 5.23, −LR: 0.27). Comparison of ROC curves showed no difference in terms of predicting peripheral artery stenosis of ≥70% between PWD and QTD (p=0.3308).

Conclusions

Interpreting PWD and QTD offers a non-invasive and cost-effective assessment method for detecting patients at high risk for coronary artery disease in the context of severe PAD.