Mean Tpe Research Articles

Learning Curve in Robotic Stereoelectroencephalography: Single Platform Experience

Learning curve, training, and cost impede widespread implementation of new technology. Neurosurgical robotic technology introduces challenges to visuospatial reasoning and requires the acquisition of new fine motor skills. Studies detailing operative workflow, learning curve, and patient outcomes are needed to describe the utility and cost-effectiveness of new robotic technology. A retrospective analysis was performed of pediatric patients who underwent robotic stereoelectroencephalography (sEEG) with the Medtronic Stealth Autoguide. Workflow, total operative time, and time per electrode were evaluated alongside target accuracy assessed via error measurements and root sum square. Patient demographics and clinical outcomes related to sEEG were also assessed. Robot-assisted sEEG was performed in 12 pediatric patients. Comparison of cases over time demonstrated a mean operative time of 363.3 ± 109.5 minutes for the first 6 cases and 256.3 ± 59.1 minutes for the second 6 cases, with reduced operative time per electrode (P= 0.037). Mean entry point error, target point error, and depth point error were 1.82 ± 0.77 mm, 2.26 ± 0.71 mm, and 1.27 ± 0.53 mm, respectively, with mean root sum square of 3.23 ± 0.97 mm. Error measurements between magnetic resonance imaging and computed tomography angiography found computed tomography angiography to be more accurate with significant differences in mean entry point error (P= 0.043) and mean target point error (P= 0.035). The epileptogenic zone was identified in 11 patients, with therapeutic surgeries following in 9 patients, of whom 78% achieved an Engel class I. This study demonstrated institutional workflow evolution and learning curve for the Autoguide in pediatric sEEG, resulting in reduced operative times and increased accuracy over a small number of cases. The platform may seamlessly and quickly be incorporated into clinical practice, and the provided workflow can facilitate a smooth transition.

Patients with Achilles Tendon Rupture Are Prone to Develop Ventricular Arrhythmia.

This study aimed to examine the ventricular repolarization (VR) disturbances of patients operated on for acute spontaneous Achilles tendon ruptures (ATRs), by comparing them with a healthy individual control group. Between June 2014 and July 2020, a total of 29 patients (28 males, 1 female; mean age: 40 ± 9.78 years; range, 21-66 years) who presented to the emergency department within the first three weeks of injury, and were diagnosed with acute spontaneous ATRs and treated with an open Krackow suture technique, were retrospectively analyzed. Fifty-two healthy individuals (47 males, 5 females; mean age: 39 ± 11.45 years; range, 21-66 years) were recruited as a control group from the cardiology outpatient clinic. Clinical data (demographic features and laboratory parameters (serum glucose, creatinine, hemoglobin, white blood cell count, and lipid profile)) and electrocardiograms (ECGs) were collected from medical records. ECGs were evaluated for heart rate and VR parameters of QRS width, QTc interval, cQTd interval, Tp-e interval, and Tp-e/QT ratio. The clinical data and these ECG parameters were compared between groups. There was no statistically significant difference between groups, regarding clinical data (all p < 0.05). Among ECG parameters, heart rate, QRS width, QTc interval, and cQTd interval were similar between groups (all p < 0.05). There were two important statistically significant findings of this research: The mean Tp-e interval was longer (ATR group: 72.4 ± 24.7, control group: 58.8 ± 14.5, p: 0.01), and the Tp-e/QT ratio was higher (ATR group: 0.2 ± 0.1, control group: 0.16 ± 0.4, p: 0.027) in the ATR group. According to the ventricular repolarization disturbances found in this study, patients with ATR may be at a higher risk of ventricular arrhythmia than healthy people. As a result, ATR patients should be assessed for ventricular arrhythmia risk by an expert cardiologist.

Effect of Sodium-Glucose Co-transporter-2 Inhibitors on Ventricular Repolarization Markers in Heart Failure with Reduced Ejection Fraction.

Sodium-glucose co-transporter-2 (SGLT2) inhibitors added to optimal medical therapy have been shown to reduce the risk of cardiovascular death and recurrent heart failure (HF) hospitalization in HF patients. We aimed to evaluate the effect of SGLT2 inhibitors on the ventricular repolarization markers (VRM) in patients with HF with reduced ejection fraction (HFrEF). 51 patients with HFrEF who had symptoms New York Heart Association (NYHA) class II-IV despite optimal medical treatment and were added SGLT2 inhibitors to their treatment were included in the study. Electrocardiography (ECG) and laboratory results obtained before the treatment and at the first-month follow-up visit were compared. QT, QTc (corrected by Bazett formula), QT dispersion (QTd), QTc dispersion (QTc-d), Tpeak to Tend (Tp-e) interval, Tp-e/QT, and Tp-e/QTc ratios were measured and defined as VRM. A significant decrease was observed in HR, QT, QTc intervals, and QTd compared to pre-treatment. While the mean Tp-e interval was 101.5 ± 11.7ms before treatment, it decreased to 93.1 ± 12.7ms after treatment (p < 0.001). There was a significant decrease in N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels after treatment [2859 ± 681vs.1266 ± 763, respectively (p < 0.001)] and QTd, Tp-e interval, and Tp-e/QTc ratio was positively correlated with the change in NT-proBNP level. The addition of SGLT2 inhibitors to optimal medical therapy in HFrEF patients positively changes VRM (QT, QTc, QTd, Tp-e, and Tp-e/QTc).

Comparison of Tp-e interval, QTc interval and Tp-e/QTc ratios between non-diabetic and prediabetic population

Aim: Increased blood glucose concentration and cardiac autonomic nerve dysfunction are associated with an increased risk of malignant ventricular arrhythmia. Tp-e interval, Tp-e/QT, and Tp-e/QTc are novel parameters used to assess ventricular arrhythmogenicity. This study aimed to compare these parameters with the healthy control group in prediabetics. Materials and Methods: The ECGs of 58 prediabetic patients (29 male, 59.74 ±13.25 years) were examined and matched with the ECGs of 59 healthy controls (28 male, 61.75 ± 12.66 years) that were matched with gender, age and body mass index. From the 12-lead ECG Tp-e and QT intervals were measured and by Bazett's formula QTc was calculated. Tp-e/QT and Tp-e/QTc proportions were also determined. Results: In prediabetic patients, the mean Tp-e interval was significantly longer than the control group (79.07 ± 8.17 vs 72.03 ± 9.77 ms, respectively; p 0.001). Also in prediabetic, Tp-e/QT and Tp-e/QTc were significantly higher than the controls (respectively 0.21 ± 0.25 vs 0.19 ± 0.03 and 0.19 ± 0.02 vs 0.17 ± 0.02; p 0.001). Other ECG parameters were similar in both groups. HbA1c levels and glucose levels were positively correlated with Tp-e / QT and Tp-e / QTc.Conclusion: Prediabetes increases the risk of ventricular arrhythmogenesis by increasing the transmural dispersion of repolarization. The addition of Tp-e interval and TP-e / QT measurements to the routine ECG evaluation of prediabetic patients can be used to predict arrhythmia risk.

Twenty-Four-Hour Measures of Heart Rate-Corrected QT Interval, Peak-to-End of the T-Wave, and Peak-to-End of the T-Wave/Corrected QT Interval Ratio During Antipsychotic Treatment.

Prolonged ventricular repolarization, measured by heart rate-corrected QT interval (QTc) prolongation, might be a biomarker for risk of torsade de pointes (TdP) and sudden cardiac death. However, the predictive value of QTc has been challenged, and a component of QTc, peak-to-end of the T-wave (Tpe), and a high Tpe/QT ratio might be superior biomarkers because they better reflect increased transmural dispersion of ventricular myocyte repolarization, which can lead to TDP. The purpose of this pilot study was to provide the first measurements of heart rate, QTc, Tpe, Tpe/QTc, and their variability over 24 hours in medication-free patients with schizophrenia, during treatment with ziprasidone or other antipsychotic drugs, and healthy controls. Subjects included 12 patients treated with ziprasidone, 30 treated with other antipsychotic drugs, 3 unmedicated patients, and 15 normal controls. Subjects underwent 24-hour analog Holter recording, and the recordings were digitized. A cardiologist blind to treatment selected multiple 10-cycle segments throughout each recording and measured the electrocardiogram metrics. Variability in QTc, Tpe, and Tpe/QTc over the 24 hours was present in all groups; 91.1% of patients and 100% of controls had 1 or more QTc values of 450 milliseconds or greater. Mean QTc length was significantly greater in the ziprasidone-treated than the non-ziprasidone-treated patients (P = 0.02). Mean Tpe was not elevated in the ziprasidone patients, whereas mean Tpe/QTc was lower (P < 0.01). The large variability in QTc, Tpe, and Tpe/QTc observed supports the need for 24-hour electrocardiogram recordings to provide an accurate assessment of risk of TdP. Heart rate-corrected QT interval alone does not capture the risk of TdP.

The impact of 21-hydroxylase deficiency on cardiac repolarization changes in children with 21-hydroxylasedeficient congenital adrenal hyperplasia.

Korkmaz HA, Özdemir R, Küçük M, Karadeniz C, Meşe T, Özkan B. The impact of 21-hydroxylase deficiency on cardiac repolarization changes in children with 21-hydroxylase-deficient congenital adrenal hyperplasia. Turk J Pediatr 2019; 61: 228-235. 21-hydroxylase-deficient congenital adrenal hyperplasia (CAH) is associated with cardiovascular risk factors such as, hypertension, obesity, dyslipidemia, and insulin resistance. It is not known whether 21-hydroxylase-deficient CAH is risk factor for atrial and ventricular arrhythmias. The purpose of this study was to compare the 12-lead electrocardiographic measures in patients of 21-hydroxylase-deficient congenital adrenal hyperplasia with those in healthy control subjects matched for age, sex, height, weight and body mass index (BMI). Twenty-five patients with 21-hydroxylase-deficient CAH and twenty-five heathy control subjects were enrolled into this observational, cross-sectional, controlled study. The evaluation consisted of anthropometric measurements, biochemical parameters, and electrocardiographic (ECG) measures. The standard 12-lead electrocardiography was performed in all patients and P-wave dispersion (PWd), QT interval, QTd, QTcd, Tp-e dispersion, Tp-e/QT and Tp-e/QTc ratios were calculated. There were no significant differences in the groups for age, sex, height, weight and BMI (median age 9.4 (1.5-16.75) years, mean weight 37.6±21.5 vs. 27.9±18.3 kg, mean height 125.4±28.9 vs. 114.7±31 cm, mean BMI 21.4±5.7 vs. 18.9±3.4 kg/m2, respectively). P dispersion and Tp-e dispersion were significantly higher in patients of 21-hydroxylase-deficient CAH compared to the healthy subjects (median P dispersion 50 (25) vs. 40 (40) ms, mean Tp-e dispersion 48±15.5 vs. 35.2±17.5 ms). Our study revealed that 21-hydroxylase deficient CAH is associated with high risk of atrial and ventricular arrhythmias in children.

Multi-operational selective computer-assisted targeting of hepatocellular carcinoma - evaluation of a novel approach in an animal model

Background: We evaluated accuracy and efficiency of a novel technique for precise ablation of HCC, combining a transarterial approach for intrahepatic tumour tracking and electomagnetic (EM)tracked navigation for percutaneous placement of ablation probes, in a porcine model. Methods: A prototype of a catheter with integrated EM-tracked reference sensor was placed via inguinal access into an intrahepatic artery. Intrahepatic tumour models were targeted percutaneously with a tracked ablation probe using EM navigation. Total positioning error (=TPE) was measured when aiming for the intrahepatic reference sensor (baseline targeting) and at defined distances relative to the sensor (offset targeting, accounting for the expected distance between the tumour and the sensor when placed in peritumoural vessels). Results: 505 targetings were performed in 6 swines. Mean TPE for baseline targeting: 2.6 ± 1.6mm. Mean TPE for offset targeting with reference sensor closest to tumour: 3.1 ± 1.6mm. No correlation between offset distance and TPE was shown (p=0.62), if the sensor was placed intrahepatically. TPE increased when placing the sensor externally (p<0.01). Mean time for navigated targeting: 13.6 sec. TPE did not differ when targeting under continuous breathing versus in apnoe (p=0.08). Conclusion: This technique allows continuous intrahepatic tumour tracking and accurate and efficient targeting of liver lesions in an animal model. It might represent a simple approach for combined ablation and TACE in a single treatment session.

Multi-Operational Selective Computer-Assisted Targeting of hepatocellular carcinoma-Evaluation of a novel approach for navigated tumor ablation.

ObjectiveTo facilitate precise local ablation of hepatocellular carcinoma (HCC) in a setting of combined ablation and transarterial chemoembolization (TACE), we evaluated accuracy and efficiency of a novel technique for navigated positioning of ablation probes using intrahepatic tumor referencing and electromagnetic (EM) guidance, in a porcine model.MethodsAn angiographic wire with integrated EM reference sensor at its tip was inserted via a transarterial femoral access and positioned in the vicinity of artificial liver tumors. The resulting offset distance between the tumor center and the intrahepatic endovascular EM reference was calculated. Subsequently, EM tracked ablation probes were inserted percutaneously and navigated toward the tumor center, relying on continuous EM guidance via the intrahepatic reference. Targeting accuracy was assessed as the Euclidean distance between the tip of the ablation probe and the tumor center (Target Positioning Error, TPE). Procedural efficiency was assessed as time efforts for tumor referencing and tumor targeting.ResultsIn 6 animals, 124 targeting measurements were performed with an offset distance < 30 mm (clinically most feasible position), resulting in a mean TPE of 2.9 ± 1.6 mm. No significant correlation between the TPE and different intrahepatic offset distances (range 21 to 61 mm, n = 365) was shown as long as the EM reference was placed within the liver. However, the mean TPE increased when placing the EM reference externally on the animal skin (p < 0.01). TPE was similar when targeting under continuous ventilation or in apnea (p = 0.50). Mean time for tumor referencing and navigated targeting was 6.5 ± 3.8 minutes and 14 ± 8 seconds, respectively.ConclusionThe proposed technique allows precise and efficient navigated positioning of ablation probes into liver tumors in the animal model. We introduce a simple approach suitable for combined ablation and TACE of HCC in a single treatment session.

A novel marker to determine arrhytmia risk in elite cyclists: T peak T end

In athletes, left ventricular hypertrophy is a physiological response upon routine active sports. If the hypertrophic cardiomyopathy is not diagnosed and treated, it can lead to sudden deaths in athletes. Not so much data is known whether or not it is favorable to use of Tp-e values in order to reflect the arrhythmia risks in asymptomatic elite cyclists. The aim of this study is to examine the risks of regular bike sport on potential arrhythmia in healthy active elite cyclists and veterans by using non-invasive cardiac tests. Study groups were: healthy volunteers (group 1, n=28, mean age 35.8±4.6), active cyclists (group 2, n=27, mean age 21±3.0), veteran cyclists (group 3, n=27, mean age 29.5±7.1 yr). All groups were underwent cardiological examinations, 12 derivation ECG records, transthoracic echocardiography investigations. Tp-e interval, Tp-e dispersion, corrected Tp-e interval, QT interval and Tp-e/QT ratio were calculated from ECG records. Tp-e intervals were measured with Tangent method, corrected Tp-e interval were measured with Bazett formula. Mean Tp-e interval results were as follows according to groups 1, 2, 3; 75.0±9.3, 88.1±7.0, 83.2±8.8 ms, respectively. The Tp-e interval, cTp-e interval, Tp- dispersion, QT interval, and SLI values were significantly higher in active cyclists than the veteran cyclists and the control group (p<0.05). Both cyclist groups had also significantly higher Tp-e interval, cTp-e interval, QT interval, Tp-e/QT, QRS time and SLI values than the control group (p<0.05). Furthermore, there were significant differences in Tp-e interval, cTp-e interval, Tp-e dispersion, QT interval and SLI values between the active and veteran cyclists (p<0.05). There were significant differences in Tp-e dispersion between active cyclists and control group or veteran cyclists (p< 0.01). Arrythmia related to Tp-e interval, Tp-e dispersion, corrected Tp-e interval and Tp-e/QT ratio are associated with long-term, intense bike sport training either in active cyclists or veterans. This can also be associated with left ventricular hypertrophy in active cyclists and remnant left ventricular hpertrophy in veterans.

Electrocardiographic measures of repolarization dispersion and their relationships with echocardiographic indices of ventricular remodeling and premature ventricular beats in hypertension.

ObjectiveTo examine the relationship between Tpeak- Tend interval (Tpe) and Tpe/QT ratio with occurrence of ventricular premature beats (VPBs) and left ventricular remodeling in hypertension.MethodsA total of 52 patients with mild to moderate essential hypertension were included, undergoing echocardiography and 24-hours Holter monitoring. Ventricular remodeling was assessed by left ventricular mass index (LVMI) using the Devereux formula and diastolic function by transmitral E and A wave velocities and E/A ratio. Tpe was measured in the precordial leads. The end of the T wave was set by the method of the tangent to the steepest descending slope of the T wave.ResultsTpe and Tpe/QT in leads V2 (r = 0.33, P = 0.01; r = 0.27, P = 0.04 respectively) and V3 (r = 0.40, P = 0.002; r = 0.40, P = 0.003, respectively) correlated significantly with LVMI. A significant inverse relationship was observed between E/A ratio and QT (r = −0.33, P = 0.01), Tpe in V3 (r = −0.39, P = 0.003) and Tpe/QT in V3 (r = −0.31, P = 0.02). Tpe in V3, V5, mean Tpe and maximum Tpe with cut-off values of 60 ms, 59 ms, 62 ms and 71 ms, respectively, associated with the occurrence of ventricular premature beats.ConclusionsThe repolarization parameters Tpe interval and Tpe/QT ratio correlate with LVMI and indices of left ventricular diastolic function and show better predictive values than traditional parameters such as QT interval and QT dispersion. Lead V3 is the best lead for measuring Tpe and Tpe/QT. These ECG indices can therefore be used in clinical practice to monitor LV remodeling and predict occurrence of VPBs.

Evaluation of Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio in patients with mitral valve stenosis before and after balloon valvuloplasty.

Objective:Sympathetic activity increases in patients with mitral stenosis (MS). The association between prolonged Tpeak-Tend (Tp-e) interval and increased sympathetic activity has been demonstrated. This study aimed to evaluate Tp-e interval, Tp-e/QT ratio, and Tp-e/corrected QT interval (QTc) ratio in patients with MS before and after balloon valvuloplasty.Methods:Thirty patients with severe MS and 30 sex-, body mass index-, and and age-matched healthy control subjects were enrolled. The severity of MS was defined following clinical, transthoracic, and transesophageal echocardiographic examinations. All patients underwent successful mitral balloon valvuloplasty. Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios were measured using 12-lead electrocardiogram. First, the abovementioned parameters were compared between patients with MS and healthy control subjects. Second, these parameters were compared before and after balloon valvuloplasty in patients with MS.Results:The mean Tp-e interval was significantly prolonged in patients with MS compared with healthy control subjects (85.02±9.12 ms vs. 75.38±6.04 ms; p<0.001). In addition, Tp-e/QT ratio and Tp-e/QTc ratio were significantly higher in patients with MS than in healthy control subjects (0.217±0.025 vs. 0.196±0.02 and 0.203±0.02 vs. 0.184±0.019; p<0.001).The mean valve area significantly increased after balloon valvuloplasty compared with that before balloon valvuloplasty (1.83±0.32 cm2 vs. 1.18±0.15 cm2; p<0.001). Compared with those before balloon valvuloplasty, Tp-e interval (85.02±9.12 ms vs. 78.06±9.2 ms; p<0.001), Tp-e/QT ratio (0.217±0.02 vs. 0.201±0.02; p<0.001), and Tp-e/QTc ratio (0.203±0.02 vs. 0.184±0.02; p<0.001) decreased after balloon valvuloplasty.Conclusion:We revealed that Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio increased in patients with severe MS. Furthermore, balloon valvuloplasty had a favorable effect on parameters associated with myocardial repolarization.

Comparison of Tpe Changing on ECG, in Pre and Post Dialysis and Post Transplantation.

BackgroundHigh incidence of premature ventricular contractions (PVCS) and arrhythmia during and soon after dialysis have been demonstrated by Holter monitoring.ObjectivesIn this study, the effects of dialysis and renal transplantation on Tpe, Tpec (corrected Tpe), QTc (corrected QT), QTd (QT dispersion), and Tpe/QT parameters as known factors in arrhythmogenicity, and also the correlation between electrolyte and arterial blood gas changing within these parameters will be assessed.Patients and MethodsIn a retrospective study, 42 renal transplant recipients were selected. Under the supervision of an electrophysiologist, information related to Tpe, Tpec, Tpe/QT, QTd, and QTc parameters before dialysis (pre-HD), after dialysis (post-HD), and two weeks after transplantation (RTX) were analyzed. Electrolyte and arterial blood gas information were also recorded. Bonferroni adjustment, repeated measures ANOVA, generalized linear models, and generalized estimating equations were used for analysis.ResultsTwo weeks after transplantation, the mean Tpe decreased to 0.052 ± 0.002, which was significant compared to pre-HD (P < 0.001) and Post-HD (P = 0.019). The mean Tpec was 0.059 ± 0.002, which, just in comparison to pre-HD, was significant (P = 0.005). In addition, the mean Tpe/QT decreased to 0.143 ± 0.005, which was significant compared to pre-HD (P = 0.018). The mean QTd was 0.066 ± 0.004, which wasn’t significant compared to before or after dialysis. The mean QTc decreased to 0.386 ± 0.004, which was significant compared to post-HD (P = 0.0003).ConclusionsTaking the role of Tpe and Tpe/QT in arrhythmia into account and amending it by a successful transplantation can be considered as a factor that decreases arrhythmia after renal transplantation compared to ESRD patients.

Evaluation of Tpe interval and Tpe/QT ratio in patients with slow coronary flow.

Objective:Slow coronary flow (SCF) phenomenon is described as the delayed opacification of the distal vasculature and angiographically normal coronary arteries. Considerable studies have suggested that the interval from the peak to the end of the electrocardiographic T wave (Tpe) may correspond to the transmural dispersion of repolarization and that increased Tpe interval and Tpe/QT ratio are associated with malignant ventricular arrhythmias. In this study, we intended to evaluate ventricular repolarization in patients with SCF by using the Tpe interval and Tpe/QT ratio.Methods:The study population included 33 patients with angiographically proven SCF and 33 control patients with angiographically proven normal coronary arteries without associated SCF. Coronary flow rates of patients and the control group were documented by TIMI (Thrombolysis in Myocardial Infarction) frame count. From the electrocardiograms, Tpe interval and Tpe/QT ratio were calculated and compared between groups.Results:No statistically significant difference was found between the two groups in terms of basic characteristics. Mean Tpe interval, Tpe/QT ratio, and Tpe/QTc ratio were prolonged in the study group compared to the control group (p<0.001).Conclusion:Tpe interval and Tpe/QT ratio were increased in SCF patients.

ASSA13-12-1 The Change of the Tpeak-Tend Interval in Exercise Test Induced Myocardium Ischemia

Objective This study aims to evaluate whether myocardium ischemia induced by treadmill exercise testing (TET) will impact on Tpeak-Tend interval (Tpe). Methods Record the electrocardiogram of positive and control group before and at the peak of TET, measure and calculate the maximal Tpe, mean Tpe, QT dispersion (QTd) and Tpe of the leads with limited ST-segment deviation. Results 1. The comparison of the corrected maximal Tpe, mean Tpe and the corrected QTd is much longer at the peak of exercise test in positive group (P Conclusions Maximal, mean Tpe, QTd at the peak of test in positive group and Tpe of the leads with limited ST-segment deviation are significantly longer, prompting that the prolong of Tpe in exercise induced myocardial ischemia may reflect the increasing of ventricular dispersion of repolarization, and may indirectly reflect the myocardia ischemia.

Abstract P195: Lack of Association between Sleep Duration and ECG Arrhythmia Risk Measures: Chicago Area Sleep Study

Introduction Sleep duration is significantly associated with cardiovascular disease risk factors such as hypertension, diabetes, and obesity in adults at low risk for obstructive sleep apnea. Although it is known that apnea increases the risk for sudden cardiac death, it is not known whether adults with short sleep duration independent of apnea have a higher risk for cardiac arrhythmias Hypothesis We tested the hypothesis that sleep duration in adults at low risk for obstructive sleep apnea would be associated with ECG measures that are known risk factors for ventricular arrhythmias. Methods The Chicago Area Sleep Study recruited 610 participants via commercially available telephone listings. Participants were screened using in-home apnea detection equipment (ApneaLinkTM) for one night to exclude subjects with apnea/hypopnea index ≥ 15. Participants wore wrist actigraphs for 7 days to objectively determine sleep duration. A 10-minute 12-lead ECG was recorded for each subject. Standard measures of heart rate, PR interval, and QTc interval were obtained along with markers of ventricular repolarization, Tpeak to Tend interval (Tpe) and spatial QRS-T angle. Signal-averaged ECG analysis was performed to measure filtered QRS duration (fQRSd), RMS voltage of terminal 40 ms (RMS), and duration of terminal QRS signals &lt;40μV (LAS). Participants with atrial fibrillation, &gt;20% ectopic beats and those using antihypertensive and sleep medications were excluded from analysis. The effect of sleep duration on the ECG parameters was estimated using a multiple linear regression model adjusting for demographics (sex, age, and race) and cardiovascular risk factors (BMI, hypertension, coronary heart disease, and diabetes). Results ECGs from a total of 504 participants (200 male, 48±8 years old) were analyzed. Mean sleep duration was 7±1 hrs, heart rate was 64±9 bpm, PR interval was 165±18 ms, and QTc interval was 424±23 ms. Mean Tpe interval was 83±14 ms and spatial QRS-T angle was 29±26 deg. The signal-averaged ECG measures of fQRSd, RMS, and LAS had mean values of 78±12 ms, 58±34 μV, and 24±9 ms, respectively. In an unadjusted model, there was a borderline association between sleep duration and QTc (β=0.004 ms/hr, SE=0.0023, p=0.08). However, that association was no longer significant following adjustment with demographics and cardiovascular risk factors. No other ECG measures were associated with sleep duration. Conclusions In a population at low risk of obstructive sleep apnea, ECG-based measures of cardiovascular risks were not associated with sleep duration. Previously reported associations between short sleep and cardiovascular events may not be arrhythmic in origin.

Tp‐e Interval, Tp‐e/QT Ratio, and Tp‐e/QTc Ratio are Prolonged in Patients with Moderate and Severe Obstructive Sleep Apnea

Prolongation of the peak and the end of T wave (Tp-e) has been reported to be associated with ventricular arrhythmias. Tp-e/QT ratio and Tp-e/QTc ratio are used as an index of ventricular arrhythmogenesis. An increased incidence of ventricular arrhythmias has been reported in patients with obstructive sleep apnea (OSA). The aim of this study was to assess ventricular repolarization in patients with OSA by using Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio. We have studied 72 patients who underwent overnight polysomnography (PSG) between the years 2010-2011 at our institution. Patients with moderate and severe OSA (23 patients; mean age: 45±10), according to the apnea-hypopnea index, constituted the study group. Patients with normal PSG (23 patients; mean age: 42±11) were used as the control group. In all patients, Tp-e interval, Tp-e/QT ratio, Tp-e/QTc ratio, as well as some other electrocardiogram intervals were measured. Independent samples t-tests were used for comparison of continuous and categorical variables and correlations were calculated by Spearman rank correlation. Although QT and QTc intervals were not different between the groups, mean Tp-e interval (81.6±11.1 msn; 63.9±7.3 msn; respectively; P < 0.001), Tp-e/QT ratio (0.21±0.03; 0.17±0.02; respectively; P < 0.001), and Tp-e/QTc ratio (0.20±0.03; 0.16±0.02; respectively; P < 0.001) were prolonged in the study group compared to the control group. Correlation analysis showed a significant positive correlation between the presence of moderate and severe OSA and Tp-e interval (r = 0.72; P < 0.001), Tpe/QT ratio (r = 0.70; P < 0.001), and Tp-e/QTc ratio (r = 0.70; P < 0.001). Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio are prolonged in patients with moderate and severe OSA patients. There is a positive correlation between the presence of OSA and Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio.

Relation Between Left Ventricular Geometry and Transmural Dispersion of Repolarization

Studies have shown an association between left ventricular (LV) geometry and complex ventricular ectopic activity. Increased transmural dispersion of repolarization (TDR), which correlates to the interval from the peak to the end of the T wave (Tpe) on the surface electrocardiogram, is linked to ventricular tachyarrhythmias. The relation between LV geometry and TDR is unknown. The mean Tpe interval, measured from leads V(1) to V(3) of the surface electrocardiogram, was assessed in 300 patients (50% men) who had normal LV systolic function and QRS duration and were categorized into 3 equal groups, which were matched by age and gender, according to echocardiographically determined LV geometry (normal structure, concentric remodeling, and LV hypertrophy). The Tpe interval was corrected for the QT interval using Tpe/QTc and was compared among the 3 groups. Compared with those who had normal LV structure, the Tpe interval was significantly prolonged in those who had LV hypertrophy and significantly shortened in those who had concentric remodeling (p = <0.0001 for the 2 comparisons). Correcting for the QT interval using Tpe/QTc yielded similar results. Thus, TDR was increased in patients who had LV hypertrophy but decreased in concentric remodeling compared with those who had normal cardiac structure. Although LV hypertrophy represents a maladaptive geometric process that results in an unfavorable electrical substrate, concentric remodeling may represent a structural adaptation that has a more favorable electrical milieu.