JTc Intervals Research Articles

A preliminary report about the detection of ventricular repolarisation in patients with non-alcoholic fatty liver disease

ObjectivesNon-alcoholic fatty liver disease (NAFLD) is a multisystem disease which can affect the cardiovascular system as well. We conducted this study to determine the cardiac effects of NAFLD such as conduction of impulse and ventricular repolarisation on electrocardiography (ECG). MethodsIn this study, we recruited patients with risk factors for NAFLD (group I; n = 23) and NAFLD patients (group II; n = 74) from Shar Hospital in Sulaimani City, Iraq. We analysed anthropometric measurements, serum fasting lipid profile, glucose levels, liver enzymes, and ECG recordings. ResultsECG recordings showed significantly longer PR intervals, significantly shorter QTcB and JTc intervals, and a higher Tp-e/QTcB ratio in group II patients than in group I patients. These abnormalities were not associated with risk factors for diabetes. The TQ duration was significantly correlated with serum alanine aminotransferase (r = 0.411, p < 0.001) and aspartate aminotransferase (r = 0.272, p = 0.019) levels. ConclusionIn our study, the presence of significant abnormalities in ventricular repolarisation suggests that patients with newly diagnosed NAFLD have subclinical cardiac stress and a higher risk of ventricular arrhythmias.

Evaluation of QRS, QTC, JTC Intervals in Congenital Heart Disease with Pulmonary

BackgroundPulmonary hypertension (PH) in congenital heart disease (CHD) affects the patient prognosis. QRS and QTC intervals prolongation in ECG may exaggerate life-threatening dysrhythmia in these patients. We aimed to investigate the correlation between QRS, QTC and JTC intervals prolongation in ECG with PH in CHD children. Materials and MethodsIn a cross-sectional study that was performed in pediatric cardiology clinic of Besat hospital (Hamadan, Iran), during 2016-2018, patients with CHD and PH as case group (n=40) were compared to simple CHD patients without any evidence of PH as control group (n=40). Based on Pulmonary Artery (PA) to systemic pressure ratio, lower than 1/2 was considered as mild PH and equal and more than 1/2 was considered severe PH; then QRS, QTC, JTC intervals in ECG and RVMPI, TAPSE in echocardiography were compared between case (PH group), and control groups. We also compared these ECG and echocardiographic findings between mild and severe PH group.ResultsThere was significant difference in QRS (p=0.005), and QTC (p=0.036) intervals between two groups, but there was not any significant difference between JTC interval between two groups (p=0.714). Of 40 patients with PH, 19 subjects were in the mild PH group and 21 subjects were in severe PH group, in which nine patients had irreversible PH or Eisenmenger syndrome. QTC (p

Ventricular Repolarization is Associated with Cognitive Function, but Not with Cognitive Decline and Brain Magnetic Resonance Imaging (MRI) Measurements in Older Adults.

We aimed to investigate the cross-sectional and longitudinal associations of electrocardiogram (ECG)-based QT, QTc, JT, JTc, and QRS intervals with cognitive function and brain magnetic resonance imaging (MRI) measurements in a cohort of older individuals at increased risk for cardiovascular disease, but free of known arrhythmias. We studied 4627 participants (54% female, mean age 75 years) enrolled in the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER). Ten-second ECGs were conducted at baseline. Cognitive function was tested at baseline and repeated during a mean follow-up time of 3.2 years. Structural MRIs were conducted in a subgroup of 535 participants. Analyses were performed with multivariable (repeated) linear regression models and adjusted for cardiovascular risk-factors, co-morbidities, and cardiovascular drug use. At baseline, longer QT, JT, JTc—but not QTc and QRS intervals—were associated with a worse cognitive performance. Most notably, on the Stroop Test, participants performed 3.02 (95% CI 0.31; 5.73) seconds worse per standard deviation higher QT interval, independent of cardiovascular risk factors and medication use. There was no association between longer ventricular de- or repolarization and structural brain measurements. Therefore, specifically ventricular repolarization was associated with worse cognitive performance in older individuals at baseline but not during follow-up.

The effects of ondansetron versus dexamethasone on electrocardiographic markers of ventricular repolarization in children undergoing cochlear implant

IntroductionCongenital hearing loss is associated with cardiac rhythm disturbances namely long Q-T syndrome. This study was designed to investigate the effect of anti-emetic doses of ondansetron and dexamethasone on ECG recordings in children undergoing cochlear implant surgery. MethodsSixty-three pediatric patients scheduled for elective cochlear implantation were enrolled in the study. Two patients were excluded as their baseline ECG showed long QT syndrome. Anesthesia was induced with fentanyl, propofol and atracurium and maintained with propofol. Dexamethasone 0.1 mg.kg−1or ondansetron 0.2 mg.kg−1was randomly administered for the participants approximately 30 min before the end of surgery. ECG recording was performed 15 min after induction of anesthesia and 15 min after dexamethasone/ondansetron administration. RR interval, QRS duration, QT interval, and Tp-e interval were measured by a blinded cardiologist. ResultsOndansetron resulted in no significant changes in RR, JTc and QTc intervals; while prolongedTp-e interval. Multivariable logistic regression analysis showed that use of ondansetron was an independent predictor of QTc prolongation after adjustment for age, gender and baseline QTc (OR = 17.94, CI 95% 1.97–168.70, p = 0.011). The incidence of postoperative retching/vomiting in ondansetron group was significantly lower than dexamethasone group. (3.2% vs. 26.7%, p = 0.011). ConclusionThe risk of arrhythmias with the use of ondansetron in otherwise healthy candidates of cochlear implant is very low. However, the drug may induce significant changes in ECG parameters. The clinical significance of these changes in patients with cardiac conduction abnormalities should be investigated in further studies.

Clinical Risk Factors for Therapeutic Lithium-Associated Electrocardiographic Changes in Patients With Bipolar Disorder.

Lithium, a common medication used in bipolar disorder treatment, can exert an inhibitory effect on sodium and potassium channels and potentially cause cardiac electrical conduction disturbance and corrected QT (QTc) prolongation. This study aimed to examine whether lithium at therapeutic levels can change electrocardiographic parameters in different groups of patients with bipolar disorder and to identify the potential clinical risk factors. Standard 12-lead electrocardiogram data before and after lithium treatment in bipolar disorder patients after at least 2-week dropout of psychotropic medications were analyzed. A total of 39 patients with bipolar disorder receiving lithium treatment were enrolled. Nineteen patients (48.7%) exhibited increased from P wave beginning to QRS complex beginning intervals after lithium treatment (mean serum level, 0.653 ± 0.247 mmol/L). Twenty-four patients (61.5%) exhibited increased a combination of Q, R, and S waves complex durations and increased QTc intervals. Twenty-three patients (59.0%) exhibited increased corrected JT (JTc) intervals. The patient group with increased QTc or JTc intervals exhibited a higher mean systolic blood pressure than did the patient group without increased QTc (134.7 ± 19.2 mm Hg vs 115.7 ± 11.8 mm Hg, P = 0.020) or JTc intervals (134.4 ± 19.6 mm Hg vs 117.6 ± 13.3 mm Hg, P = 0.054), respectively. Biochemical and hemodynamic parameters were comparable between patients with and without increased a combination of Q, R, and S waves complex durations or from P wave beginning to QRS complex beginning intervals. Elevated systolic blood pressure may be the risk factor for the ventricular conduction delay in bipolar disorder patients receiving lithium at therapeutic levels.

Sex and race differences in J-Tend, J-Tpeak, and Tpeak-Tend intervals

To facilitate the precision of clinical electrocardiographic studies of J-to-Tpeak (JTp) and Tpeak-to-Tend (Tpe) intervals, the study investigated their differences between healthy females and males, and between subjects of African and Caucasian origin. In 523 healthy subjects (254 females; 236 subjects of African origin), repeated Holter recordings were used to measure QT, JT, JTp, and Tpe intervals preceded by both stable and variable heart rates. Subject-specific curvilinear regression models were used to obtain individual QTc, JTc, JTpc and Tpec intervals. Rate hysteresis, i.e., the speed with which the intervals adapted after heart rate changes, was also investigated. In all sex-race groups, Tpe intervals were not systematically heart rate dependent. Similar to QTc intervals, women had JTc, and JTpc intervals longer than males (difference 20–30 ms, p < 0.001). However, women had Tpec intervals (and rate uncorrected Tpe intervals) shorter by approximately 10 ms compared to males (p < 0.001). Subjects of African origin had significantly shorter QTc intervals than Caucasians (p < 0.001). Gradually diminishing race-difference was found for JTc, JTpc and Tpec intervals. JTc and JTpc were moderately increasing with age but Tpe/Tpec were not. Rate hysteresis of JTp was approximately 10% longer compared to that of JT (p < 0.001). In future clinical studies, Tpe interval should not be systematically corrected for heart rate and similar to the QT interval, the differences in JT, JTp and Tpe intervals should be corrected for sex. The differences in QT and JT, and JTp intervals should also be corrected for race.

Possible association of papillary muscle hypertrophy with the genesis of J-waves

BackgroundAlthough J-waves have been known to be associated with vulnerability to ventricular fibrillation, their electrophysiologic mechanism remains to be elucidated. The papillary muscles (PMs) of the left ventricle (LV) have been recognized as the target site of radiofrequency ablation for ventricular arrhythmias. However, the relationship between PM hypertrophy and J-waves has not been investigated. ObjectiveTo investigate the electrocardiographic characteristics, including the J-waves, in patients with solitary PM hypertrophy. MethodsWe studied 101 patients with PM hypertrophy without LV hypertrophy (PMH group) and 159 age- and sex-matched control subjects (control group). The parameters of the 12-lead electrocardiogram and the echocardiogram were compared between the two groups. ResultsCompared with the control group, the PMH group had significantly higher incidence (15% vs. 33%, p=0.001) and amplitude (0.17±0.06mV vs. 0.28±0.17mV, p<0.01) of J-waves; significantly longer QRS, QTc, and JTc intervals (p=0.0001, p<0.0001, and p<0.05, respectively); significantly greater Sokolow–Lyon index (p<0.001); and significantly greater LV wall thickness and LV mass index (p<0.0001 for each). Multivariate logistic regression analysis showed that only the PM hypertrophy was an independent predictor of the presence of J-waves. ConclusionPM hypertrophy was related to the genesis of J-waves.

Evaluation of Electrocardiographic Ventricular Depolarization and Repolarization Variables in Type 1 Diabetes Mellitus.

BackgroundThe risk of cardiovascular events and sudden death increases with type 1 diabetes mellitus (T1DM).ObjectiveTo evaluate electrocardiographic markers of arrhythmias in T1DM patients.MethodsElectrocardiographic parameters reflecting ventricular depolarization and repolarization, namely, QT, QTc, QTd, QTdc, Tp-e, JT, and JTc intervals and Tp-e/QT and Tp-e/QTc ratios, of 46 patients diagnosed with T1DM were retrospectively analyzed and compared with 46 healthy age-, sex-, and body mass-matched controls. Correlations between T1DM duration, hemoglobin A1c (HbA1c), and ventricular repolarization variables were analyzed. P values lower than 0.05 were considered statistically significant.ResultsDiabetes duration was 16.6 ± 7.1 years, and HbA1c was 10.81% ± 3.27% in the T1DM group. In comparison with the control group, heart rate, QTc, QTd, QTdc, Tp-e and JTc intervals, Tp-e/QT ratio (p < 0.001), and Tp-e/QTc ratio (p = 0.007) were significantly higher in T1DM patients. T1DM duration and HbA1c levels were significantly correlated with QTc, QTd, QTdc, Tp-e, and JTc intervals and Tp-e/QT and Tp-e/QTc ratios.ConclusionsIn T1DM patients, potential electrocardiographic repolarization predictors were significantly increased in correlation with disease duration and HbA1c levels. These findings may contribute to the understanding of sudden cardiac death in patients with T1DM.

Abstract 17194: Incremental Value of JTc Interval in Improving Risk Stratification for Life-Threatening Ventricular Arrhythmias in Patients Considered Low Risk by LVEF

Introduction: ICD implantation is recommended in patients with LVEF&lt;35%, while those with LVEF between 35 to 40% are not considered at high risk for primary prevention ICD implantation. A subset of these patients develops life threatening ventricular arrhythmias (VA) and improvement in risk stratification may help identify and implement life-saving intervention. Hypothesis: Prolonged repolarization is a marker of electrical instability and JTc interval on ECG could provide prognostic information in patients with LVEF 35-40% incremental to that from LVEF. Methods: Patients ≥18 yr with no history of VA and an ECG and echocardiogram obtained at initial encounter between 11/2011 to 12/2016 with long-term follow-up were identified. The incremental predictive ability of JTc interval on improvement in risk stratification for VA was determined by receiver operating characteristics (ROC) curve, integrated discrimination improvement (IDA) and net reclassification improvement (NRI) analysis. All tests were performed at a 5% level of significance. Results: Out of 29,700 pts that met inclusion criteria, 1,102 (3.7%) had LVEF 35-40% (mean age 70.5±14.6 yrs, 49% males, CAD 67%) and 24,894 (84%) LVEF &gt;40% (65.9±16.3 yrs , 61.8% M). Over the mean follow-up of 4.6±4.2 years, the incidence of VT/VF/cardiac arrest was 16.1% in patients with LVEF 35-40% compared to 4.1% with LVEF &gt;40%. For every 50 ms increase in JTc interval above 300 ms, the risk for arrhythmic event in LVEF 35-40% increased two-fold (Odds Ratio=1.83 (95 % CI 1.72-1.94, P=0.013). Incorporation of JTc to LVEF improved the C statistics (95% Confidence Limit) in the model with only LVEF from 0.56 (0.54-0.57) to 0.72 (0.70-0.73) for the model combining LVEF and JTc. In addition, NRI was estimated at 0.57, which was statistically significant with p values &lt;0.001 while IDI was estimated as 0.015 with p values &lt;0.001 for the model incorporating JTc to LVEF. Conclusions: In patients with LVEF 35-40% considered low risk for life threatening VA by EF, incorporating JTc interval information improved risk stratification and identified those who subsequently developed VT/VF or cardiac arrest and thus identifies a subgroup that can benefit from prophylactic ICD implantation.

Association of low-moderate urine arsenic and QT interval: Cross-sectional and longitudinal evidence from the Strong Heart Study

Epidemiologic studies suggest that chronic exposure to arsenic is related to cardiovascular disease (CVD), but the pathophysiological link remains uncertain. We evaluated the association of chronic low-moderate arsenic exposure and arsenic metabolism with baseline difference and annual change in ECG measures (QT interval, JT interval, PR interval, QRS duration, and QT dispersion) using linear mixed models in the Strong Heart Study main cohort (N = 1174, median age 55 years) and family study (N = 1695 diabetes-free, median age 36 years). At baseline, arsenic exposure was measured as the sum of inorganic and methylated species in urine (ΣAs) and arsenic metabolism was measured as the relative percentage of arsenic species. Median ΣAs and Bazett heart rate-corrected QT interval (QTc) were 8.6 μg/g creatinine and 424 ms in the main cohort and 4.3 μg/g and 414 ms in the family study, respectively. In the main cohort, a comparison of the highest to lowest ΣAs quartile (>14.4 vs. <5.2 μg/g creatinine) was associated with a 5.3 (95% CI: 1.2, 9.5) ms higher mean baseline QTc interval but no difference in annual change in QTc interval. In the family study, a comparison of the highest to lowest quartile (>7.1 vs. <2.9 μg/g creatinine) was associated with a 3.2 (95% CI: 0.6, 5.7) ms higher baseline QTc interval and a 0.6 (95% CI: 0.04, 1.2) ms larger annual increase in QTc interval. Associations with JTc interval were similar but stronger in magnitude compared to QTc interval. Arsenic exposure was largely not associated with PR interval, QRS duration or QT dispersion. Similar to arsenic exposure, a pattern of lower %MMA and higher %DMA was associated with longer baseline QTc interval in both cohorts and with a larger annual change in QTc interval in the family study. Chronic low-moderate arsenic exposure and arsenic metabolism were associated with prolonged ventricular repolarization.

Tp-e interval and Tp-e/QT ratio in clinically stable pediatric heart transplant recipients.

A study of the T wave peak-to-end (Tp-e) interval, the Tp-e/QT ratio, and the Tp-e/QTc ratio in pediatric heart transplant recipients (HTRs), a group which has a higher risk of sudden cardiac death than the normal population, has not previously been reported. The aim of this study was to assess alterations in ventricular repolarization using the Tp-e interval, Tp-e/ QT ratio, and Tp-e/QTc ratio in clinically stable pediatric HTRs. A total of 13 clinically stable HTRs, 13 patients who had undergone cardiac surgery (CS) under cardiopulmonary bypass, and 16 healthy controls under 18 years of age were retrospectively evaluated. No significant differences were observed between the HTR, CS, and control groups in terms of QTc, JTc interval, and T wave amplitude (p&gt;0.05). The Tp-e interval (p=0.001), Tp-e/QT ratio (p&lt;0.001), and Tp-e/QTc ratio (p=0.001) were significantly higher in the HTR group compared with the CS and normal control participants. The Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio were elevated in stable HTRs compared with the normal and CS groups.

Hidradenitis suppurativa and electrocardiographic changes: a cross-sectional population study.

Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease, recently associated with metabolic syndrome, subclinical atherosclerosis and increased risk of cardiovascular disease. To investigate the hitherto unknown electrocardiographic (ECG) changes associated with HS, which have recently been associated with significant cardiovascular burden. Data were obtained from the cross-sectional Danish General Population Study (GESUS). HS diagnosis was based on a validated self-reported questionnaire; 404 individuals met the HS diagnosis criteria and 19 001 controls without HS were identified. Severity of HS was staged according to a modified Hurley score. The ECG parameters of heart rate (HR), PR interval, QRS duration, JTc interval and QTc interval were obtained from 12-lead resting ECGs. We investigated the difference in means by unpaired t-test or anova. HR was significantly higher [mean difference 2·3 beats per min (bpm), 95% confidence interval (CI) 1·2-3·4; P < 0·01] when adjusting for age and sex, but when adjusting for multivariates, there was no significant difference (0·3 bpm, 95% CI -0·7 to 1·4; P = 0·52). Severe HS was significantly associated with increased HR across all models (2·9 bpm, 95% CI 0·7-5·1; P = 0·01). Mean QRS duration was significantly shorter in the group with mild HS but not in the groups with moderate and severe HS. Mean resting HR in patients with severe HS was significantly higher compared with controls. Given that resting HR is associated with increased risk of all-cause and cardiovascular mortality, and that patients with HS have increased risk of cardiovascular events, this finding is potentially important, easily testable and intervenable.

Effects of propofol on ventricular repolarization and incidence of malignant arrhythmias in adults

BackgroundPropofol is commonly used for procedural sedation in interventional electrophysiology. However, ventricular arrhythmias under Propofol have been reported. Our aim was to investigate ventricular repolarization and incidence of ventricular arrhythmias under Propofol infusion in adults with cardiac arrhythmias. MethodsQRS, QTcB (Bazett), QTcFri (Fridericia), JTc, measurement of T peak to Tend time (Tp-e) at baseline and under Propofol infusion was performed in 235 patients. Screening for unexpected ventricular arrhythmias was performed in 1165 patients undergoing EP procedures under Propofol. ResultsA significant prolongation of Tp-e under Propofol infusion (79.7±17.3 vs. 86.4±22.5ms, p<0.001) and of QTcFri (429.3±35.8 vs. 435.5±36.5, p=0.033) was detected. No significant change of the QTcB interval, JTc interval or QRS duration was observed. One case (0.09%) of ventricular fibrillation during rapid ventricular pacing under Propofol occurred. ConclusionAlthough transmural dispersion of ventricular repolarisation is increased under Propofol, incidence of malignant ventricular arrhythmias is low. For evaluation of QT interval under Propofol, Fridericia's correction formula should be used rather than Bazett's formula.

Among patients with left bundle branch block, T-wave peak to T-wave end time is prolonged in the presence of acute coronary occlusion

BackgroundAssessing the effect of myocardial ischemia on ventricular repolarization in the setting of left bundle branch block (LBBB) poses a challenge due to secondary prolongation of the QT interval inherent in LBBB. The T-wave peak to T-wave end (TpTe) interval has been noted to prolong during myocardial ischemia and correct after reperfusion in patients with normal conduction. Here we compare the TpTe intervals of patients with LBBB both with and without complete acute coronary occlusion (ACO). MethodsRetrospectively, emergency department patients with LBBB and symptoms of myocardial ischemia were identified both with angiographically-proven ACO and with No-ACO. The longest QT, JT, and TpTe intervals were analyzed. ResultsThe ACO and No-ACO groups consisted of 33 and 129 patients, respectively. The mean TpTe was longer in ACO (103.6ms [95%CI 98.5–108.7]) compared to No-ACO patients (88.6ms [95%CI 85.3–91.9]) (P<0.0001) and this held true after correction for heart rate. In ACO versus No-ACO, the TpTe also more frequently exceeded prolongation cutoffs of 85ms (30 [90%] versus 69 [54%]) and 100ms (25 [76%] versus 42 [33%]) (P<0.0001 for all). The mean QT, JT, QTc, and JTc intervals were not significantly different between the groups for either the Bazett's or Rautaharju's correction formulas. ConclusionsIn patients with LBBB on the ECG, the TpTe is longer and more frequently prolonged in patients with ACO compared to patients without ACO. Future studies of ventricular repolarization in patients with LBBB should include analyses of the TpTe interval.

Systematic ajmaline challenge in patients with long QT 3 syndrome caused by the most common mutation: a multicentre study.

Overlap syndromes of long QT 3 syndrome (LQT3) and the Brugada syndrome (BrS) have been reported. Identification of patients with an overlapping phenotype is crucial before initiation of Class I antiarrhythmic drugs for LQT3. Aim of the present study was to elucidate the yield of ajmaline challenge in unmasking the Brugada phenotype in patients with LQT3 caused by the most common mutation, SCN5A-E1784K. Consecutive families in tertiary referral centres diagnosed with LQT3 caused by SCN5A-E1784K were included in the study. Besides routine clinical work-up, ajmaline challenge was performed after informed consent. A total of 23 subjects (11 female, mean age 27 ± 14 years) from 4 unrelated families with a family history of sudden cardiac death and familial diagnosis of the SCN5A-E1784K mutation underwent ajmaline challenge and genetic testing. Sixteen subjects (9 female) were found to be heterozygous carriers of SCN5A-E1784K. Ajmaline challenge was positive in 12 out of the 16 (75%) mutation carriers, but negative in all non-carriers. Following ajmaline, a significant shortening of the rate-corrected JT (JTc) interval was observed in mutation carriers. The baseline JTc interval was significantly longer in mutation carriers with a positive ajmaline challenge compared with those with a negative one. Overlap of LQT3 and BrS in patients carrying the most common mutation is high. Therefore, ajmaline challenge represents an important step to rule out potential BrS overlap in these patients before starting sodium channel blockers for the beneficial effect of QT shortening in LQT3.

Heart Rate-Corrected QT and JT Intervals in Electrocardiograms in Physically Fit Students and Student Athletes.

In literature, data on the prevalence of prolonged and shortened corrected QT (QTc) have shown considerable variability. The aim of the study was to compare QTc and JTc intervals of competitive student athletes and noncompetitive sport participants to QTc cutoff points used in athletes. A group of 485 physically fit candidates for the study of kinesiology (139 female and 346 male candidates) aged 18-20 participated in the study. Basic anthropometry, field fitness test, cardiovascular, electrocardiograms measurements, and blood sampling for lipid profile were conducted. The prolonged QTc according to European Society of Cardiology criteria was found in 2.9% of female and 4.3% of male students. When the "Seattle criteria" were used, the proportion of prolonged QTc was 1.44% in female and 0.29% in male students. The shortened QTc according to the Seattle cutoff points was presented in 0.7% of female and 2.0% of male students. The JTc over 400 ms was found in 0.72% of female and 0.29% of male students. The JTc shorter than 320 ms was presented in 0.7% of female and 1.1% of male students. No significant differences were found between students involved in competitive sport and those involved in recreational sporting activities. Female students had lower body mass index and blood pressure values, better blood lipid profile, and lower uric acid concentrations. In conclusion, the Seattle criteria markedly decreased the proportion of prolonged QTc in student athletes, particularly in male students. It seems that the JTc interval could be a better parameter than the QTc interval for the estimation of specific repolarization time in physically fit university students.

Electrocardiographic repolarization abnormalities and increased risk of life-threatening arrhythmias in children with dilated cardiomyopathy

Life-threatening arrhythmia events (LTEs) occur in ~5% of children with dilated cardiomyopathy (DCM). While prolonged QRS duration has been shown to be associated with LTEs, electrocardiographic (ECG) repolarization findings have not been examined. We sought to determine the associations between ECG repolarization abnormalities and LTEs in children with DCM. A single-center retrospective review of children with DCM was performed. LTEs were defined as documented ventricular tachycardia or fibrillation requiring medical intervention. Three pediatric cardiologists, blinded to clinical events, evaluated ECGs obtained at the time of initial referral. Kaplan-Meier survival and Cox proportional hazards analyses were used to evaluate time to LTEs. A total of 137 patients (mean age 7.8 ± 6.7 years; 75(55%) male patients) with DCM (mean ejection fraction 35% ± 16%) were included; 67 patients (49%) had a corrected JT (JTc) interval of ≥340 ms, 72 (53%) had a corrected QT (QTc) interval of ≥450 ms, and 41 (30%) had abnormal T waves. LTEs occurred in 15 patients at a median of 12 months (interquartile range 3-36 months) after the initial ECG. Patients with LTEs had a longer JTc interval (371 ± 77 ms vs 342 ± 41 ms; P = .02) and a longer QTc interval (488 ± 96 ms vs 453 ± 44 ms; P = .01). In survival analysis, a JTc interval of ≥390 ms (hazard ratio [HR] 4.07; 95% confidence interval [CI] 1.12-14.83; P = .03), a QTc interval of ≥510 ms (HR 6.95; 95% CI 1.53-31.49; P = .01), abnormal T-wave inversion (HR 11.62; 95% CI 2.75-49.00; P = .001), and ST-segment depression (HR 6.91; 95% CI 1.25-38.27; P = .03) were associated with an increased risk of LTEs, even after adjusting for QRS duration and amiodarone use. Repolarization abnormalities are common in children with DCM. Certain ECG repolarization abnormalities, such as significantly prolonged JTc and QTc intervals, may be useful in identifying patients at risk of LTEs.

Abstract 15631: The Hemodynamic Determinants and Physiologic Correlates of QTc Interval Using Impedance Cardiography in Heart Failure

Background: Prolonged QTc interval is a known risk factor for adverse cardiac events, including sudden and non-sudden cardiac death. Understanding the determinants and physiologic correlates of QTc can guide the proper strategy for the primary prevention of sudden death in high risk patients. Methods &amp; Results: This was an observational study that recruited ambulatory heart failure patients (NYHA I-III) from an outpatient clinic in NL, Canada. In supine resting position, consented participants underwent non-invasive 12-lead ECG and hemodynamic monitoring using BioZ Dx Impedance Cardiography (Sonosite Inc., WA, USA). ECGs were evaluated by a reviewer blinded to clinical data. Participants with pacing (n=12) or left bundle branch block (n=9) were excluded. Three measures of interest were automatically computed: (1) QTc interval (i.e., from QRS onset to T offset), (2) QRS duration (i.e., from QRS onset to QRS offset), and (3) JTc (i.e., QTc interval minus QRS duration). Effect sizes were computed using Pearson’s r coefficients. The final sample (n=23) was 62±13 years of age and 70% male with LVEF of 34±10%. The mean QTc was 441±39 milliseconds, and 10 patients (43%) had prolonged QTc (≥450 milliseconds). QTc interval negatively correlated with cardiac output (r= -0.57), and positively correlated with systemic vascular resistance (r= +0.57), as well as thoracic fluid content (r= +0.43). QRS duration alone was not specifically associated with any hemodynamic parameter, but JTc interval positively correlated with total arterial compliance (r=+0.42). Conclusions: In heart failure patients, we interestingly found that increased systemic vascular resistance results in QTc interval prolongation, where repolarization time is specifically influenced by arterial compliance. This suggests potential benefit from antihypertensive therapy targeted at lowering systemic vascular resistance in those with prolonged QTc/JTc. Nevertheless, these intervals need to be interpreted with caution in patients with thoracic fluid overload (e.g., pulmonary edema).

Electrocardiographic Markers and Left Ventricular Ejection Fraction Have Cumulative Effects on Risk of Sudden Cardiac Death

ObjectivesThis study assessed potential improvement in predicting risk of sudden cardiac death (SCD) by adding selected risk markers from the 12-lead electrocardiogram (ECG) to the measurement of left ventricular ejection fraction (LVEF). BackgroundNovel strategies to improve risk stratification for SCD are needed. Given the modest odds associated with most individual risk markers, combining multiple markers may be a useful approach. MethodsFrom the ongoing Oregon Sudden Unexpected Death Study, SCD cases with pre-event LVEF data available were compared with those of matched control subjects with coronary artery disease. Resting heart rate, QRS duration (QRSD), and JTc intervals were measured from archived ECGs prior to and unrelated to the SCD event. Independent odds of SCD for individual and combined ECG markers were calculated. ResultsSCD cases (n = 317; 67.9 ± 12.9 years of age) were more likely than controls (n = 317; 67.9 ± 12.8 years of age) to have LVEF ≤35% (26% vs. 11%, respectively). Mean heart rate, QRSD, and JTc were significantly higher in cases (all p < 0.0001). In adjusted analyses, higher heart rate (odds ratio [OR]: 2.6 [95% confidence interval [CI]: 1.8 to 3.7]), QRSD (OR: 1.5 [95% CI: 1.0 to 2.5]), and JTc (OR: 2.3 [95% CI: 1.6 to 3.4]) were independently associated with SCD. When ECG markers were combined, SCD odds progressively increased with 1 (OR: 3.4 [95% CI: 2.1 to 5.4]) and ≥2 elevated markers (OR: 6.3 [95% CI: 3.3 to 12.1]). Addition of ECG markers to an adjusted model with LVEF improved discrimination (C statistic improved from 0.642 to 0.724) and net reclassification (by 22.7%; p < 0.0001). ConclusionsCombining selected 12-lead ECG markers with LVEF improves SCD risk prediction and warrants further investigation in prospective studies.

Электрокардиографические показатели электрической нестабильности миокарда у больных синдромом обструктивного апноэ-гипопноэ во время сна и впервые выявленной артериальной гипертензией

Objective. To study the rate of long QTc and JTc intervals in sleep-wakefulness cycle, and also their relationship with severity of obstructive sleep apnea-hypopnea syndrome (OSA) in patients with newly diagnosed hypertension (HTN). Design and methods. 24‑hour multifunctional monitoring was conducted in 59 male patients (age 38,0 ± 7,7 years old; body mass index 33,8 ± 5,4 kg/m 2) with elevated office blood pressure, who did not receive any medications. All patients had two or more risk factors of HTN. Organ damage was identified in 12 (20 %) patients. The long QTc interval was defined as 450 msec or more, automatic analysis was performed using 8‑lead dynamic ECG. Results. OSA was diagnosed in 40 (68 %) patients: 17 patients had mild sleep apnea (apneahypopnea index, AHI, from 5 to 14 episodes per hour), the rest of the patients had moderate and severe OSA (AHI from 18 to 97 episodes per hour). Nineteen (32 %) patients without OSA were included in the comparison group (AHI less than 5 episodes per hour). There was no differences in average heart rate during assessed time periods between the groups. There was a direct positive correlation between duration of QTc and JTc calculated separately for periods of wakefulness, sleep and AHI and hypoxemia index. Conclusions. More than 50 % of patients with newly diagnosed AH and OSA without associated cardiovascular diseases demonstrate changes in myocardial repolarization throughout sleep-wakefulness cycle. These changes are associated with the number of apneas/hypopneas and the severity of hypoxemia during sleep